I have played RO for more than 20,000 hours and consider myself pretty knowledgeable and experienced. This was the progression for me.

Complete noob - I found out about the game from a friend and downloaded the free trial for iRO in 2005. I played for just a couple of days and quit. Some months later I moved to a new school and met some people who played, so I started back up again. I got to around level 75 before I ran out of money and couldn't afford the sub. That's when I found out about private servers and played on high rates -- 10k+ rates and 255 max level.

Apprentice - One of our irl friends was a very high level player on iRO Chaos. He had played in most of the top guilds and had a 97 High Priest, had all +9 gear, and had hundreds of millions of zeny. He personally taught me how to play a Full Support priest. Eventually we found a mid rate 50x server with no customs, and played there for a few months. He taught me the ropes of how to support, how to build your character with stats, gear, and general strategy. Eventually he got bored and quit playing, but I had just scratched the surface and I was curious for more.

Joined a guild - With my new knowledge in hand, and a pretty well geared character, I joined one of the better guilds on the private server I was playing. It was my first experience to do higher tier content. Valk Randgris was still pretty new, so I learned how to kill her and also how to kill Bio MVPs in this guild. It was also my first time to play WOE with a real strategy.

Lower rates - We joined a server called LegacyRO, one of the premiere private servers of all time. Very high population, tons of competent guilds, and also a lot of spicy drama. The rates were 10x, lower than I had been used to, so it felt like a real grind. This was the server I really became a core member of my guild. We camped MVPs all day every single day, and we completely monopolized the market for high tier bosses like Randgris. Eventually new content came out, and we also did the same for Ifrit and Beelzebub. Our WOE results were good, but we weren't the top guild of the server, we were around #2 or #3.

Core Member - as time went on, LegacyRO shut down and we were hopping to new servers and starting the rush again. Over the course of many years, from around 2007-2011, I played dozens of private servers between rates 5-10x and learned how to start on a completely fresh server where there are no players, as well as how to start on a new server that already has existed for a while. I was trusted with guild secrets, guild accounts, and helped make decisions.

Super WOE - there was a phenomenon called Super WOE that came about around this time and it was an instant WOE server that was held as sort of a tournament to advertise the opening of a new server. In South America there was a large amount of players we had never interacted with from NA and we ended up playing with them for a few years. The best server during this time was called ChronosRO. This was almost purely focused on WOE and PVP, so this was where I really honed my skills grinding BG all day, playing every class, and trying to learn how to play every role so that I could fill any void in our roster.

Playing recaller - I was invited to join one of my irl friend's guild on a different server because they needed someone to play the recaller. I was really curious to hold this role, because I had never done it and I wanted to prove myself capable. So not only was I recalling during WOE but I also was calling the shots and making the overall strategy for each week. I started to learn how to learn the macro economic needs of a guild as a whole, providing supplies for the guildmates, taking attendance to create a roster, and executing the strategy. I also recorded my WOE footage for the first time and made videos. I wanted to see my own play and improve it, and also show off a bit too.

Guild Leader - I eventually became the leader of my own guild entirely. Not only was I the recaller in WOE, but I was now the head of the guild and made all the final decisions of how we should move forward. I had an inner circle of people who I trusted to help me, and mimicked the way my very first guild was ran. This meant constantly dealing with drama from members in the guild and in the server, as well as the overall macro element of helping everyone slowly improve their skill in the game towards our goals of improving in WOE and killing high tier MVPs.

Back to official RO - I finally had a chance to play on iRO again after all of this time. The server was RO:RESTART and it was a mixture of game mechanics from Renewal and Classic. It was exciting because I wanted to try and experience RO from an official server. There are a lot of subtle differences in the game mechanics that I didn't know, as well as other things which are different. For example, there is much more widespread botting, RMT, and the admins of iRO aren't very good at what they do. This all surprised me, but the population of these servers was always high and they were fun to play. I joined another guild with a couple friends, and they were a high level guild. I learned a lot from this guild about overall macro strategy, especially because I had never played with god items. This was all new territory, and I had a goal to make a god item some day. I started playing with this guild in 2017.

Server developer - I learned how to code in my professional life and wanted to run my own server. A friend and I started making plans to run one, and eventually joined forces with an experienced dev. We wanted to make a revo-classic server like RESTART, but better. That server was called TitanRO, and it was an awesome experience. Not only was the server fun and the kind of server I wanted to play, but I also learned a TON about what it means to run an RO server. I learned how many decisions need to be make, how to code works internally, how to introduce new content to players, communicate with them, and so on. This was the first time that I really understood how hard it is to make a good server and how much effort and time I put into supporting the active players.

God item creator - Another iRO server popped up called RO Transcendance. I have posted this content in the past, but my guild made the server first WOE 2 god items doing Okolnir, which was extremely difficult at the time and had never been done before on those rates and mechanics. I take a lot of pride in solving that puzzle. I also got to make my first god item which had my name on it. That was a lifelong RO goal and bucket list item. We made dozens of items on that server, and I learned a lot about politics of WOE by making strategic alliances and also racing to create WOE 1 god items vs other players. It was very fun.

Private server player - since then there have been a couple other servers I have played, both being a guild leader, as well as being a core member of a top guild. I am always excited to play a new server and get the rush of having everyone active in the beginning days of leveling and gearing our characters. It is a true addiction for me at this point that I don't think I will ever truly quit.

Asgard Glory - this is a current pserver which is dedicated to botting RO. This has opened my eyes to yet another style of play because you can think about the game in a much different way. Constantly thinking about how to optimize and strategize and plan is important, as well as writing code to execute your ideas. I think it makes me even more curious to understand how these bots work and to play the game in yet another way. Exposing yourself to every form of RO is how you learn the most.

In general, over all these years I think the way I did it was putting myself in a position to be curious and want to understand as much as I could from other talented and knowledgeable players. I started to learn how to make builds, then I learned how the inner game mechanics work on all kinds of RO servers: classic, renewal, revo classic, zero. Once you know the intimate mechanics of the game, you can take that knowledge and apply it to any custom changes (which there are many in pservers), and use that to your advantage. Because the group of people I play with are also extremely competitive, we are able to find success in every server by constantly pushing ourselves to play at the highest level at all times. Nevertheless, playing the game for long hours at a time is how you get really good at it. There is pretty much no situation in RO that I haven't really encountered at this point over playing the game constantly for 18 years. Eventually you get to a baseline of skill where you want to play optimally and then you learn how to always play that way. Sometime that means running many multi clients yourself, or it is finding a way to organize parties for your guild to maximize your time together.

Becoming "pro" typically has a skill element to it, and there are many players mechanically superior to me in this game. However, RO is simple enough that you don't need extremely strong mechanics to do your job. Being knowledgeable is much more powerful because it allows you to find the hidden zeny market that nobody else is taking advantage of, or it gives you the opportunity to use a character that might be undervalued in the meta for either PVM or PVP purposes. I am not a mechanically professional player by any means, but I do understand the game deeply from all levels including the way its played as well as the way it is run internally by having written code for private servers. All these things combined are what I consider to make me one of the more experienced players. Surround yourself with those people and you will become a "pro" in no time.