Honestly, the best way to go is to start putting yours together yourself, piece by piece, so you gain an understanding of how mods work and can trouble shoot problems that may come up later with full UI packages.
Use small mods to start, like Chatmod and OmniCC.
Then move onto things like Pitbull, Cartographer, Nugie's Combo Bar, Fubar, and EEPanels.
There, I pretty much just listed all the mods I use - and my UI is quite sexy.