Don't put the thesis off for too long or you'll never write it!
Ask for the subject and start working on it little by little!
These days diplomas and degrees are still very important, no?
That's the thing, I don't have a subject. I had one in mind during last winter but that came to nothing because... I don't know. I guess it was too different from what I'd been doing professionally. My current strategy is to wait while a suitable subject comes up that's related to my work.
And no, I wouldn't say a diploma is very important. Having a bachelor's degree - yes, but a master's is just a bonus. I had no trouble finding work without one. Maybe it's different in other fields, I don't know.