These are both issues that can be resolved with practice. GOAT is knacky as hell. After about 2 months I can get it to work with a relatively new deck of cards about 70% of the time. (What's sick is I guessed the method correctly before I bought andthensome. If I can, so can a lot of spectators, so don't count on it wowing unless you've performed well before hand) I still haven't got the knack. It's like asking how do you juggle. You just keep throwing balls in the air for a few months until your body works out how to handle throwing and catching them.
As for portal, I'd point out 2 things. The pop move is the least important part of it, and is obvious without some performance thrown in.
Getting the card out, 1) Put fewer cards in the left hand spread, less weight more pop. 2) The timing is knacky also. You just have to keep doing it.
3) don't spend too much time on this. It's a good effect, but really....without some serious performance thrown in, it doesn't really hold that much water in front of a camera alone. A bit of misdirection to the correct hands however and it looks like the card appeared. People looking in the wrong place and you're busted and it cheapens what is a very nice idea for an effect.
Short answer, practice more and figure this out for yourself. You'll be better at the effect for it.
