I’d suggest not playing Quaver. The community there is pretty toxic and their approval process for charts means only a handful of people get to dictate what is/isn’t ranked. They all seem to like the keyboard spam rather than charts that actually make sense.
If you’re interested in 7 or 8-key rhythm games, I’d suggest looking into Beatoraja instead. It is part of the BMS community which is an offshoot of IIDX/Beatmania. Learn to play that one well and you can approach pretty much anything else and do well.
As for tips, start slow and don’t get too frustrated. There is definitely going to be a learning curve. Also, do not switch your keys to a linear layout, leave them staggered. You’d be shooting yourself in the foot muscle memory-wise.
Main thing to do is learn how to read groups of notes rather than the individual notes themselves.