Staying lean and gaining size are not meant to be done together-for most guys anyways. Once you're happy with your size(like that will ever happen? lol), you can cut up, and try to put lean muscle on only. That way you'll still feel like you look OK while trying to gain size. Plan on having 3-5 yrs in the gym before you get to this point. Until then, train hard and heavy and put away a lot of chow and don't cut back until you start getting too fat. Doughnuts by the dozen washed down with a half gallon of milk every night worked wonders. (after I met my good caloric requirements for the day)
This is the reason a lot of guys don't compete. Once you start dieting you lose some strength and size and even though you lose weight, you still aren't ripped. This is when most guys say fuck it. It's when you go beyond this point of initial weight loss, and forget about the usual poundages you do on exercises for a few weeks that the lines/cuts start to show. Once you get there feeling wimpy is much easier to deal with since now you're looking more bodybuilder-like. Remember, chicks couldn't care less how much you bench, but ripped abs will definitely increase your chances of getting some tuna.