Repo's I use

[fijiman]

Except for the repo's that come pre-installed in Cydia I have drastically cut down the number of repo's installed by myself to 4.
The more repository you add the longer it takes cydia to load.

1 iHacksRepo - ihacksrepo.com/
2 SiNful iPhone Repo - sinfuliphonerepo.com/
3 xSellize - cydia.xsellize.com/
4 TheiPhoneSpot Repo- theiphonespotrepo.net/.apt/

To add a repo in Cydia :

Press Manage > Sources > Edit > Add

Between these 4 nearly every paid Cydia app is cracked.

[fijiman]

Just want to add what I think are some of the more important tools needed to fix/install/repair/delete...etc

From Cydia you should have installed on your idevice

1 sbsettings
2 ifile
3 open ssh
4 Mobile Terminal