in pro-tools it is super easy to do a punch... i have seen so many people do so much extra work with using extra tracks and everything to get it to work... it is soo much easier than that... here is what you do:
if you bring up the transport control you will see a time on it for pre and post roll times... this is what will help you do your punches... if you do not see the pre and post rolls on the transport than check the view and make sure it is in extended or whatever it is called...
find the begining of the word, part of word, bar, phrase or whatever part you want to punch... if you are just gonna punch from this point and continue... than that is all you need... set the pre roll time and go into record... it will play as long as you set the preroll until it hits the cursor at which point it will automatically go into record... (make sure that your playback is set to autoinput under the operations menu so that you hear the previous part before the punch)... as soon as you hear the part before it, rhyme along with yourself to keep it from sounding like a punch... have to make sure that you are at the same vocal tone and level...
now, if you want to punch just the word or whatever... than put the cursor at the beginning of it, and either drag and select or shift select to the end of the punch... or you can cut (command or ctrl E) and then find the end and do the same... and then just select the seperate region that you just created... now that you have the punch selected... select the post roll time and set it to anything... can be as long as you want... you can just stop it on your own... it is just so that it doesnt automatically stop at the end of the punch (keep in mind that you will not hear anything on that track after the punch finishes though)... (also, make sure that you are not set on looprecord mode when you try this)
... this should get you going... if you have anymore questions, dont hesitate to just respond back and ask...
(last tip to it... to keep from having digital clicks and pops at the punch points... zoom in REALLY close when selecting the cursor position... click vaguely and then zoom in to fine tune it... your goal is to select a spot at a zero crossing... this is where the waveform is neither going up nor down but is just a straight line cross the center... doesnt have to be perfect, but the closer to the zero line at the punch the better chance for a smooth clean punch...)