I want to reiterate the importance here of what Torg said. It's huge.
Be careful of theory-hammer. You might think that new unit sounds good on paper, and find out you fall short, or doesn't fit your playstyle/strategy, etc.
Proxy units in some friendly learning games. Don't feel you need to blow your paycheck to get a full army right off. Especially since you'll end up like most of us with boxes never assembled, never painted, and you won't be able to keep up the modelling side of things.
Don't be afraid to ask, wouldn't bug most because it's not about winning, it's about learning a 'game'.
I once made a cardboard replica of a Necron monolith, and spray painted it black, and such was able to use it for a few games and see if I even liked it. Then, dropped some cash.
Playing games helps you find out what kind of player you are.
A must spam every overpowered unit and leaf blow my opponent off the table.
Balanced list for strong, but friendly games.
Don't mind the squishier units because they look pretty (do custodes even have squishy units?) 🤪
Start playing, don't wait. My first 3 games were two 500 point and a 750 point. I wouldn't go past that until you've gotten some core play in. However, 1000 points is a sweet spot to get to because games get more balanced and full feeling. 500 and 750 can be hard to beat a 2+ save, etc. Then again, these aren't about trying to beat you, they're about game mechanics. Then get more games in..
Eventually you'll want 1500, then 2000 to finish off a normal battle army. HOWEVER, at this point you should be nearly a veteran and don't rush this. You'll find yourself 'behind' assembling and pains in your wallet if you go too fast. Patience and playing the 'long' game will help. 😁
We usually do an escalation league, which really helps, but with Covid I don't know when I'll be able to run the next one at the clubhouse.
Lastly, you'll find this group is usually friendly and always willing to help. However, I find this hobby in general is mostly pretty helpful.