If it is your first Bike kit I would build it OOTB to give you a feel for Bike models before starting to customise & Super detail.
Standard cheap forms of detailing are:
Replacing the supplied hydralic lines and wiring with thinner ones.
Opening the holes in the Brake discs and thinning them( no need for PE Kits).
Adding Custom tune Pipes and similar.
Adding new Hose connectors.
Thinning the fairing.
etc.
If you were building a Harley or similar you could go way further rake the forks, raise the handle bars, shorten the rear suspension, etc.
My feeling from your post is that you are not too familiar with Motorbikes(might be wrong), if you build a "used" Bike rather than the average "new of the shop floor" build that most do than there are many little touches that can make your Kit look better.