Blocking Trepidation

I've knitted all the pieces for Starsky. They are waiting patiently to be blocked. I'm very afraid to take this next step. The last thing I blocked was this:

...it GREW and I never wore it after taking this picture. I don't want the same thing to happen again. I read on someone else's blog that they steam blocked their pieces and they turned out lovely but this yarn itches me and I want it to soak in Eucalan. Does anyone have any pointers for me before I take the plunge?