I use a pyramid system for weights. I do a weight of which I can only do 6 reps of, then do a slightly lower weight with 10reps and finally do half the weight of the 10reps but do 30 reps. This has really done the trick in building up muscle. I do 3 sets of this exercise for whatever muscle groups I am doing. Another thing - do different muscle groups on different days - the main one not to combine is your biceps and triceps these two should be done on different days. As you use shoulders a lot with tricept exercise this means that the tri's and shoulders get done together and bi's and pecs get done on another day.

I have been going 5 days a week with the altering muscle groups thing, and having sat and sun off. Food wise I just grab a bannana about half an hour before exercise and then have some lean white meat and/or fish (without batter!) in the evening after the exsercise. Make sure you drink a lot of water - don't bother with lucozade - as that does sweet FA for most people from experience. I try and get through a 2litre bottle from half an hour before going to the gym to the half hour after that. Staying hydrated is very important for muscle tissue regeneration.

A big thing I would recommend is plan out your exercise otherwise you will wander around aimlessly just dabbling with each machine - get a routine going, and jot down what weights you are on each couple of days/week. This routine works for me.

Like I said I am no expert but this is what works for me.

P.S. remember to stretch and warm up (perhaps do a cycle or a row) before doing weights - pulled muscles or even torn ones are not much fun.