Think carefully about what exactly you’d like to work on, and why. Does a lack of self-confidence interfere with communication? If so, what are the reasons behind this? Do you rarely have the opportunity of talking in the target language? Or do you feel the need to work specifically on your pronunciation? Perhaps you could consider joining an oral skills or discussion group. You could also focus on your pronunciation on the internet, both by listening to good speakers and by actively working on stress and intonation. Most importantly, lower the threshold and talk whenever the opportunity arises, also in situations beyond the classroom.