The most important thing for a beginner to remember...

[OneLoveBoomer]

... is that you can win your league, even if every other player is rather experienced. I won my first year in my major FBB league... haven't taken first in it since!

[wrveres]

The 2nd most important thing.
Don't play in public leagues.
The season is 6 months long. Nothing like having your league shot to hell by May. We hear horror stories of it every year around here.
Check here, and chances are you will find a solid league of owners that actually play most of the season.
With Public Leagues, you will be lucky to get 3-4 managers actually checking their fantasy teams.

and the 3rd most important thing is, never take baseball advice from anybody named Buckner or Mookie.

[RocketsDWM]

4th - Dont panic in April or May when your hitters/pitchings arent doing well. They will turn it around.

[bigh0rt]

4th - Dont panic in April or May when your hitters/pitchings arent doing well. They will turn it around.

Not necessarily. Analysis should be done on a case by case and player by player basis.

[RocketsDWM]

I meant to say the 1st round players for the most part. Obviously scrutinize the performances of guys like Shelton a year ago. But guys like Pujols, Tex, Utley etc. will be fine.