I have been practicing on logotypes for a contest on 99designs.com. Contest in general is about winning a prize but also something you can learn from. On 99design people who wants a logotype, illustration, website design etc. can make a contest where designers submit there work and the contest creator can then chose the design he or she likes the best. It is good for practicing too because you can follow guidelines and that makes it easier when you will try to practice designing.