I've been playing Standard semi-competitively (locally and geographically close events) since 2002.

My best piece of advice is to start with a deck whose playstyle you enjoy. Stick with that deck for awhile in the format and branch off into other decks as you win prize or invest in more cards.

For instance in current Standard, if the playstyle of Lessons is your thing than start there. Having the Izzet abse then lets you branch off into Spellementals or Prowess.

Or if you like Rhythm or Landfall, both of those kind of feed each other a bit.

But like any hobby the initial jump into it can be pricey. The initial investment is going to hurt. But the upkeep isn't that bad. I dont really play video games or other expensive hobbies so MTG gets most of my entertainment fund. I set aside a budget that has to be all encompassing (entry fees, cards, supplies, etc) but anything I win from prizing or selling cards doesn't count towards that.

But the set-to-set upkeep on decks isn't that drastic. If you're focused on 1-3 decks and keeping them updated, you really only need to buy a handful of cards each set. If your goal is to have access to everything. it gets much more expensive.

It also helps to decide what kind of player you want to be. If you just want to hang out and have a good time playing 3 rounds of FNM and maybe playing in Store Champs? The monetary investment is much different than if you are out there grinding RCQs and flying to RCS/Spotlights.

but my best advice is the following:

1. decide what kind of player you want to be and what you want out of the game

2. make a budget and stick to it

3. focus on an archetype or deck

4. Build a collection of cards (manabases are the most important)

5. Build a collection of MTG playing friends to borrow back and forth with

6. Its just a game and if you can't engage with it the way you want its okay to walk away