Making your rankings and projections alot of work is what its all about!!!
As far as what I do is.......
I take all the players I want to rank, usually.....
25+ C
30+ 1B/DH
25+ 2B,3B,SS
100+ OF
100+ SP
50+ RP
I then look up each players stats he has had every year he has been in the bigs or I will look at his minor league numbers as well if he is a rookie or second year player. My emphasis will be on what that player has done the last 2 or 3 years but I do like to see what kind of "career" years he has had or "bad" years.
I then will make my own prediction on what that player will do for the current year. After I have all my predictions down I will then put in my own formula that takes my prediction #'s and gives me a final number and I rank my players based on that number the formula gives me.
Talk about alot of work!!

But to tell ya the truth its the most fun time of the year when it is ranking/prediction/projection time, then draft day is that much better!!!
Jason