DoctorP82 hit on the most imporant factor imo, especially breakfast.
My home brew is water slightly cooler than body temperature (not "cold"), with raw sugar, honey and lemon slices.
Banana as a snack.
If I'm struggling I use electrolyte tablets, potassium salt and magnesium, but I try to avoid needing to 'boost' like that. IMO it only indicates that I've been eating crap... like a burger for breakfast hahaha.
Prep for races I use a commercial powdered drink the day before, which I find gives real benefits in cramping and burst power (for me at least), but otherwise the lemon/sugar keeps me fresh/alert/hydrated just as well I think.
For recovery I have flavoured milk on top of a carb starter before a propper meal.
You might find some interesting info here:
Australian Institute of Sport :: Hydration
And amungst the other pages on there, generally non-commericially orientated.