Welcome mate, I got my Flame 172 not long ago and I love it - you shouldn't be disappointed.
Out-of-the-box a 172 is great and needs little improvement if its mainly going to be a fun run-around. If you plan on going to meets & track days you may get suckered into wanting the usual mods:
- Intake
- Exhaust
- Springs / Coilovers
- Remap
- Wheels
If you join the club you'll get full access to the forum and you'll be able to do your research on all of the above; and access to the Parts For Sale section, for which you'll be able to pick up loads of parts 2nd hand and dirt cheap.
The big one is making sure your Cambelt & Auxillary belt changes are up to date, if you've got any cash spare and this job is due - it should take precedence over anything else. When I bought mine, they were due, so it was factored into the price and then I got them done straight away; then engine felt refreshed and more keen to rev after the job, but the Dephaser Pulley was changed along with the Throttle-body being cleaned so they'd have been contributing factors for sure.
More often than not though, a refresh of the standard suspension components will give you the best results and make the car feel incredibly tight and handle the way it was designed to, as the original rubber parts will not be in great stead now on our 172's.
172 Cup wishbones too are a decent idea, that help improve the handling as the geometry is improved by using them compared to the standard 'Full Fat' 172 wishbones.
I have a Poly-bushed dog bone engine mount which is the one near the gearbox and it makes the gear change feel very tight compared to a standard/old mount, that's worth a thought.
Hopefully that gives you a bit to think about for now anyway...
Make sure you pop some photo's up when you get it.