problem:
after turning off the iPhone, you get the screen ‘connect to iTunes’.
solution:
you have to do a jailbreak again :/

problem:
after using blacks0w wifi stops working (iPhone is unable to find any network)
solution:
you should reset network settings by navigating to Settings > General > Reset > Reset Network Settings and then reboot the iPhone.

problem:
after jailbreaking your device with blackra1n you might’ve noticed that YouTube app is throwing a message saying ‘Cannot connect to YouTube’ and also you will notice issues with push service.
solution:
these issues are caused by hackactivation. here’s the solution.
1/ launch cydia
2/ select ‘manage’
3/ tap ‘add’
4/ give it ‘http://cydia.iphoneil.net/’ and tap ‘add source’, then ‘done’
5/ now search for ‘pushfix’ and install it
6/ after install, reboot
7/ go to settings, enable ‘wifi’ again
8/ after enabling ‘wifi’, reboot again
9/ that’s it. youtube and push fix done! :)

problem:
more problems and solutions coming soon!

if you have any other problems, please describe them in comments.
i’ll try to find a solution for you! :)

how to do a proper jailbreak with blackra1n?
0/ your iphone should be like out-of-the-box, no software installed etc.
if you have any apps installed, restore it to the factory defaults!
1/ go to www.blackra1n.com and download a copy of blackra1n
one is for mac and another is for windows. choose yours.
2/ connect your iphone to your computer.
3/ close itunes.
4/ click ‘make it ra1n’ button.
5/ your iphone will reboot.
6/ wait about 15 seconds.
7/ your iphone should turn on again :) it’s jailbroken!