Learn how to navigate the regs certainly, but focus on the fish largely. Rake will just kill you playing against players of a similar skill level to yourself.
Exploiting both fish and regs to the fullest extent requires using a HUD and studying the game (studying the RIGHT material, so ignore most stuff that is not going to teach you about micro/low stakes cash games). You'll find more edges that way.
If you're finding fish and doing well at exploiting them you can obviously be much tighter against the tags, lags and nits, rather than battle them in close spots. There is no reason to tilt against the better players at all, when you have stats on them most are playing very face up most of the time down at the lower limits. You CAN exploit the regs too though, you just have to know the right spots. This is where a HUD really helps. Knowing how they behave when it comes to folds and c bet on all streets, and how often they go to showdown (and win it), and their aggression on particular streets, or knowing if they are only rarely defending their blinds, can all really help you find good spots to
bluff and good spots to just lay down.
You dont need to get out of line at all, but when you see someone you have 350
hands on is a 22/17/2 who folds only 30% vs a flop C Bet but goes on to fold 72% of the time on the turn... it should be pretty obvious that you can profitably exploit them on the turn by
bluffing a lot and just giving up if they fight back. The same logic can be applied to many spots against them.
Do shop around when it comes to sites. Some are fishier than others. Do look for the softest site. Do look for the fish and try to play more pots against them, isolate to get others out of the way where it makes sense. Don't feel like you need to battle the regs at every chance and fight for every pot with them, but do learn the easy spots to exploit them as it can a bit to your win rate.