I'd say start with Titanium Backup. Run a full backup of all apps and system data, then save a copy of that offline somewhere. Personally I did both that and an nandroid backup in TWRP (see the development section) prior to doing anything.
Then I'd go into Titanium Backup and start freezing applications that are unwanted. Personally I never uninstall them straight off, instead I freeze and see how the device responds to that. If all goes well I keep the app frozen, if not I defrost it. Since I'm not pressed for storage space yet I have not uninstalled any system apps, merely froze them. If you do decide to uninstall things be sure that this is something you want to do and that there will be no ill effects.
I'd also grab Xposed Installer and start experimenting with modules (there's a thread in the apps and themes section about Wanam, I think I listed some modules that I use there).
I've done so many tweaks to my tablet I've lost track lol.