As an ex-beginner (is that a category of poker player?) I'll add my own two little bits of advice for playing online:-

Concentrate on one form of poker (low stakes no limit for me) and make sure you only research this form. What's the point of playing tennis if you are taking advice on becoming a good table-tennis player?

Take your time! It's so easy to go into panic mode when there is a big bet against you (especially when playing more than one table) - don't make this mistake. There is always plenty of time to make the right call.