In my opinion, ditch the liquid masks and follow Swanny's guide here: http://www.swannysmodels.com/Canopies.html
I learnt how to mask canopies soley from that link, and I've never had dramas with paint bleeds, lifting of masks etc. As everyone above has said, the trick with masking tape is to cut in very small strips and then burnish well.
I've tried two types of liquid masks, one was maskol (purple colour) and another was the "Mr..." range - blue colour.
The blue "Mr Mask" (or whatever it's called) was completely useless and it ended up fogging some of my canopies (despite using a Future equivalent first).
The Maskol is ok, but i framed the canopy outlines first with thin strips of tape, then painted it on the large areas of exposed canopy.
However, I can't find anything that removes Maskol from my paintbrushes and I ended up ruining a brush every time I used it. So now, (when i do use it) I only use it for wheel wells and pour it in.
Anyhow, I digress.
Read the above link, get a good metal rule, a sharp blade and a good cutting surface - like a piece of glass or porcelain and then give it a go.
FYI, i airbrush, but if you hand brush, you might have some issues with bleeding.
It takes time, but it's worth it. My nightmare was masking all the canopies on a 1/72 TBF Avenger. I took two nights to do, but it looked amazing when done.
One downside to using tape though - I haven't figured out how to mask circular frames - such as on the Avenger, the rear gunner has a small oval frame. I ended up hand painting that.
Chris.