Here are some cheap modifications you can do, just an idea wherever you do them is entirely up to you
Couldn't help but noticing you have that ugly grey/black vinyl on the side of the doors, that Fiat put on; under this is exactly same as your paint work, I believe HGT's don't have that vinyl.
All you need to remove them, is a hairdryer to heat it up but ONLY do it for 5 minutes no longer unless you want to damage the paint work! Then peal it off and get Autoglym Intensive Tar Remover which is £6.49 from Halfords get an old rag and wipe it on, then to get the residue off just use an old credit card or something similar to scrape it off that won't damage the paint work.
Now onto the wing mirrors, I highly suggest C/C them it will make the car stand out! I've done this on mine and it looks so better than the cheap looking plastic look! When getting the colour for the car you can normally find under the bonnet or go Fiat and ask them for the colour code.
There's a guide on here how to C/C them, heck if you feel like going crazy on C/C do your door handles too!
Lastly, optional but (personal taste) get the sporting bumpers I believe you can pick them up off eBay for quite cheap or pop to your local scrappy and ask for them or take them off a dead punto.
Well that's my ideas there for you
Keep up the good work, it's looking nice!