Don't just install anything from Cydia. Not everything is for your iOS, or even an iPhone.
Always check compatability with your device and whatever tweak you may want to install.
I would YouTube "Best jailbreak tweaks for iPhone 4S on 5.0.1"
That will give you a good idea of what to install.
Some starters.
I would install
Activator
IntelliScreenx
biteSMS
KuaiDial (must add this repo: kuaidial.googlecode.com/svn/deb/)
Springtomize 2
ProTube
Callbar
KBShortcuts
No Updtae
SnoozeOrStop
TetherMe (if you dont have a tethering plan, but want to tether anyway. The best out of all tethering tweak; P.S.; MyWi is a rip off.
WeeTrackData
MultiCleaner
Multifl0w
AppInfo
Music Controls Pro (if you are an avid music listener)
Caffeine 2
Those a some of the things I have installed with no problems at all. And every one of those tweaks I mentioned are tweaks I would never consider "not" having.