What's your routine like? You could have a high protein meal after a workout , perhaps whey protein since it's easier to absorb, not to mention more convenient putting it in a shake. BCAA's (Branch chain amino acids) before and after workout will help with recovery. Food high in carbohydrates after a workout helps you recover your energy. I've tried ribose in the past which helps with recovery after a hard workout when I've been away from exercise for a while.

Some people recommend supplementing l-glutamine, which I don't think is a bad idea but I don't see the necessity in it. There's some literature that supports that glumamic acid from protein being converted to glumamine within the body. The way that I see it, if you're getting getting enough protein you don't need to take glutamine with it. I still take some after a hard run, or sometimes when I need to curb my appitite (it does help in that regard). Keeping hydrated is important as well.

There's nothing wrong with a three-days-a-week plan, if you're increasing the number of days that you lift, you might want to lower the volume (reps and sets), and take it more gradually. Breaking up your routine according to muscle groups will allow you to do more still.

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