An amportant lesson for beginners in RC is that there is no magic number as far as props are concerned. You might hear someone insist that you have to run such and such. Baloney. The best prop in an application is the one that lets the plane perform the way you want it to. Use the advice as guidelines-but experiment until you find something you like. It would be reasonable to start with an 11-6 APC or Master Airscrew. But try 11-5s while you're at it. Also try TF woods in that size range. I would also try a 12-4 in a couple of brands. The higher pitch props will give you more speed (in general) and the flatter pitch props will give you better climb. The larger props won't "wind up" (gain speed) as much in a dive. Play with them. You'll find a few that make you say No Way Will I Do That Again and then you'll find the one that you say Ah-That's It! I swear I've seen guys abandon airplanes that didn't fly to suit them without trying a different prop. Dumb!
And learn to balance your props while you're at it. Well worth the effort.
Best of luck, and enjoy!