'stress' is the most hard one for English learners. Try these two words 'man' and 'land'. If you can pronounce 'a' sound right, you should feel that the tip of your tongue is tensed, otherwise, that's wrong. To pronounce the ending 't' sound in 'can't', you don't need to aspirate the way too hard; only to make sorta pause at 't', and quickly slide over. You are talking about casual speech while I am guiding ppl to the standard direction. You set up a high goal for yourself. But anyways, good luck!
Try this link: http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=can%27t
Try this link: http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=can%27t