Dear guys, I'm about to create a new Buddypress website

Dear guys,
I'm about to create a new Buddypress website and I will need quite a lot of graphic customisation.
Can you suggest any theme or any procedure in order to make it easier when it will be time to upgrade to future versions?
With my previous experience it's been a real pain to upgrade with the standard theme and all my custom CSS....
Thanks for any suggestion!

Francesco