Few threads on how to tune an N/A car? I found loads by just doing a few quick searches!
As for tuning it depends how much you have to spend, you could spend your money on a Performance Exhuast, Stainless manifold, Induction kit such as a GSR kit, change spark plugs and leads to performance ones (Basics)
Or you can go a little bit further and get a performance chip and the Tricker 40mm Tb and also make your BHP more effective by removing weight!
And if you really want to go all the way you can consider a Turbo (which im sure there is many hundreds of threads on Turbos) or a full N/A Tuning session with GSR, Wolf Direct and or many others which will cost into the £2000+ range but will give you way more power.
Hope this helps
Adam