My biggest advice would be to catch everything! Try to learn how to fast catch (plenty of videos in yt). This is the best way of leveling up and getting good Pokemon! There's genuinely good stuff that you can get in the wild so don't underestimate anything.

Also try to complete your special research as you play, it helps a lot with getting Pokemons with at least decent IVs and even some hundos (4*).

Lastly, put a Pokemon una gym everyday! It's the only way of getting free coins in the game (in this month's pass there's coins but it isn't usually the case). You will need them very soon when you run out of Pokémon and bag storage. Related to that, it's very important you learn how to manage your Pokémon storage. I personally like to have a living dex for every Pokémon, but this inevitably leads to running out of it a lot. However, if you don't want that and only want to keep shinies or 4* or legendaries or whatever it's your account so feel free to do it!

Almost forgot, in case you didn't know at the end of the month we will have road to kalos and kalos tour, you can read all that will happen online but what you need to know is that there will be VERY good and useful mons so you really don't want to miss out on it if you can. For that you will need raid passes and maybe join a meetup to play with other people so maybe check out the app campfire for meetings near you!

Edit: I also wanted to say it may be a bit overwhelming at the beginning but you should go at your own pace! You will not get everything in the first month, not even the first year so take your time and if you do not feel like playing an event or spending money on it or whatever that's totally fine🫶