When it comes to customization it's really all up to you. I've had people tell me time and time again that it doesn't matter what someone else tells you, it's your car and as long as you like the look/feel of it then you're doing it right. I've come to adopt that philosophy and I think it's the best way to go. Just think of some things you think would look cool, and then search and see if there are any kits or parts needed and do it. If you want to get really crazy you can custom fabricate stuff for it yourself which is something I'm working on with a few random things on the interior.
in summary, it's all up to you brochacho.
yep. I said brochacho.