Completely agree, mischief motivates you like none other.

I started out by making batte.net bots for Starcraft. They were super hard but there was plenty of open source code to leech and copy off of in the beginning. Later on, I managed to learn how it all worked and pieced together which allowed me to be able to write them from scratch. This was no easy task and I started proramming like this. It entailed understanding network programming, reverse engineering, how to code in general, how to send/receive packets, and all the fundementals associated.

Make a bot for anything or any game, scripting bots to do automated things that are annoying to do manually generally has a great sense of sanctification. Making an IRC bot is easy, start to get into more challenging things like non-plaintext protocols.

If that's too complex join a community that has already done this so you have something to go off of.

The most important thing is to do something you'll have fun with and still learn. Create something that either fixes a need for yourself or for you to gain an advantage in or something you'll get to see people use.