I guess for me I didn't have a clear plan and at time made rash decisions or was 'sheep like' in my thinking without considering the consequences. This approach can leave you open to mistakes. The worse being letting a non renaultsport mechanic do my cambelt. Although like Paul says, common mistake.
For example,
V6 airbox is a great mod. No real downside but by the time you've bought the box (if you can find one) pipe, plate and relocated battery in boot, theres no change out of £500.
Throttle body. Another good mod. The problem being is you really need to remap car cause if feels like it pushes the power further up the rev range. So a £80 mod now needs a £300 remap. Alright if you've not had one.
Remap. One of the first things you do when buying a clio. So you remap, £300. Then you decided you want a V6 airbox so another £300, then you decide to fit TB...you see where I'm going if you don't have a plan and patience...
Decat. Great mod but does create a flatsport thats hit and miss to remap out. Change the airbox or TB, you notice it more...yep another remap.
Cams. The clio should have come with them standard. Forget the idea of its only 10-15bhp. Its not the point. Not about power. Makes driving the car so much better I can't tell you but its £1500 big ones.
Its been one crazy ride and love the NA experience. Just wished I had more patience and a better plan. Hindsight is an exact science though. I would encourage those to do the same with caution but the finished product makes driving it a pleasure.