here are brands to look for... fox farms, general hydroponics, technaflora (the boost line), and advanced nutrients.. those are the best (imho) 4 brands on the market.. time tested... very reliable..
get a 2 or 3 part system.. 3 parts are the best... but 2 parts are fine...
you can also get additives like blossom/flower boosters, veg and flower enhancers, root boosters, stuff that increases the uptake of nutrients, stuff that helps protect the plant from diseases and other stressers.. and the list goes on...
you could use some molasses to help with carbs for the plant.. it also acts as a natural mild fungicide.. and during flowering it'll fatten and densen up your buds...
neem oil is a great all natural pesticide/miticide.. it can be sprayed weekly to prevent outbreaks of pests.. it can be root fed to work from the inside out (pests dont like the taste.. so they wont eat it).. it is also used to control outbreaks of pests if you have them...
those are a few options..
if you use the right soil additives and make a good soil mix from the start the need for somethings becomes less... or you can always just let the rain give them what they need and just let them go with little "care" at all...