I want to get rid of the oak grain as much as possible but want something easy to use. Thanks in advance!
Many companies have "Grain-fillers", and most are pretty easy.
Call around to paint-stores, etc.
FPE's Brushing-Putty and Swedish-Putty are fantastic though!
NOT the cheapest, but they sand-off nicely if you're using quality papers.
Final sanding with ~ 220-ish grit is mandatory though for that "near glass" finish!!
I primed and painted some, and the grain was filled with just the primer and paint. Good quality paint with 100% acrylic resin binder and high solids content. If the grain were extremely deep, I would just get a floor grain filler like Famowood.