Ok so you have a jailbroken device now. The first things I always download are:
*SbSettings: Shortcut app that allows you to swipe the statusbar and instantly access options like screen brightness, 3G/Edge, airplane mode and more. You can also download more toggles in Cydia. Using the options within SBSettings allows you to hide icons, add the date to your stausbar and launch your phone into safe mode through the power menu.
*Add Install0us. This is to get paid apps free. Only do this if you won't feel bad about it. http://hackulo.us/forums/index.php?/topic/112062-how-to-install-installous/
*Add insanelyi: If you followed the last step you know how to add a source now. So add this one: repo.insanelyi.com<-- that allows you to get Cydia apps for free, like iFile
*Download winterboard: Allows you to skin different aspects of your phone
*Download ifile: This lets you explore the files on your phone. It's mentioned in one of my previous posts.
*Download Bytafont and a ton of fonts: enough said
This is just a taste to get you started. Feel free to ask any questions on the blog or email me @ email@example.com