"Sliding" (tip #1) definitely helps when I remember to do it. If you've got the kind of stutter where you go too hard into the first word and end up blocking, it does takes the tension out to ssssssssslide into the first syllable. Percussive sounds (P, T,B etc.) are a bit trickier, but trying to open your mouth slightly to let some air our rather than forcing the sound can take the tension out. Definitely a good idea to go to regular therapy though. I gave up with mine because our health service was so overburdened they weren't consistent enough (they dropped me after two years because I'd been on the register for too long...), but it really does help to refocus and experiment without the pressure to perform.