Welcome Matty, fine vintage you have there
1. Change to a YTX 14 battery and get an optimate (see threads on here for recommendations)
2. Change the relay to the Yamaha one (check thread for part number)
3. Change the gearing to 15/42 or 16/44
4. Adjust the throttle to zero play and have the throttle bodies balanced
5. Have the suspension overhauled and set for your weight and style
6. Fit decent tyres (see numerous threads for the big debate)
7. Mod the airbox - see Hookeds mighty fine airbox kit or see Badgers thread on modding (Sprockers too) a standard airbox.
8. End can of your choice to release the sound and lose the weight of the original
9. Power Commander 3 and dyno set up
10. Mpl slave for the clutch
After that little lot, if you want more, then ask again :thumbup
Most importantly, enjoy and keep it sunny side up