There are a bunch of free mods you can start with like:
-Trim the rear mud flap
-remove the ugly front horn (there are 2, not sure why you need 2)
-remove the back seat and hardware (you can get a suction seat later)
-remove the belt guards (some advise against it but I have 26,000 miles an no problem)
-remove the reflectors on the forks
-relocate the ugly rectifier under the bike
-clean up the hoses just in front of the tank on the left side
-"flip and grind" (lower the rear)
Then there are inexpensive mods like:
I hated the (off color) heat shield on the rear rotor and wanted off asap. You can remove it and order shorter bolts for the front rotors to replace the longer bolts on the rear.
Powder coat anything you can unbolt that you want a different color. I like black if you could not tell.
Then look at other bikes and see what you like. Exhaust and Bars are usually a good place to start.
Good Luck! Happy modding!