HI Michael, May I offer my own suggestion, as I started here nearly 2 years ago, with little idea of how to proceed, and have become "addicted".
I keep exact records of run times for each sub project I run, for each PC and GPU type. It really shows you where you get good credits, for the input you make.
The higher yielders, as mentioned below will get you started and keep you interested as well. It's great fun to read the messages and see the opinions, you'll learn a lot here from very smart people (not me ;-))
Try SGS, PPSE, GFN15, GFN 16. You'll get primes and then you can study the "harder ones too"
Best wishes and good luck.
PS The Tour de Primes from 1st Feb might yield you a prime or two and some good badges.