I flew yesterday first time.
All my mistakes and successes are recent.
I put together a US Aircore trainer.
Definitely made some mistakes putting it together but fixed them as I went. Joined a club and got help trimming the plane before maiden voyage. Instructor took off and landed otherwise it was mine the rest of the time :-)

Things of note I have learned
Putting together the plane taught me alot about what each piece does and how it works.
Bought a OS 52 FS new. Probably a bad idea. This size engine won't last you long. A cheaper 2 stoke alternative will work just as well. Even cheaper to buy here instead of new.
Buy a decent radio. I bought a Futaba 6xa. Several used ones running around. There is a market for them if you want to get out and they are flexible enough to take you a couple of levels up.
Computer simulator software good
Instructor a must have
Club adds value to the whole experience

There are alot of people giving free advice out there. Listen to them. Don't settle for the standard answers, tell people what you want and what your goals are and they can point you in the right direction.