Hexagons are measured across one edge, not across the entire hexagon. Now with that said, the size hexagon you choose is really personal preference.
To help you decide, answer these questions (don't post your answers) --
1. how long do I want to work on this? The smaller the hexagon, the longer it will take to finish
2. Do I want an entire quilt of hexagons or do you just want to learn the EPP technique? In that case, make a placemat.
I'm in the process of making a quilt with hexagons. I started out with a 2" hexagon (side measurement not across) and decided that it was really too big for what I wanted. So I dropped down to the 1.5" size and I was much happier with that.
I use the freezer paper technique for my hexagons. There's a tutorial here:
http://sewmanyways.blogspot.com/2009...r-piecing.html
I find the fabric doesn't shift like it normally did when I used regular paper hexagons. Yes, it's more time intensive, but it's also cheaper.