the harder ones to distinguish are the words fool and full. Especially since they are pronounced differently in different regions. The way I pronounce them, you can actually hear a difference in the words. The word fool has a dipthong and the word full does not.
A dipthong is two syllables combined to form one. For example the word say; the sound 'seh' is combined with "ee". So, when you sound out the word, you don't pronounce it seh-ee with 2 syllables but rather 'say' with one syllable.
Fool is formed with the sounds foo and uhl, instead of two syllables foo-uhl, you pronounce it in one, fool.
Full is pronounced with a single syllable, fuhl. almost like the word fun, but with an l at the end instead of an n.
The other words are easier to distinguish.
shot is pronounced sh(aw)t. To hear the sound, just make a list of as many rhyming words that you can think of. You will soon be able to distinguish it easily.
shot, got, lot, rot, cot, snot, fought, bought, sought, hot, not, pot, dot, knot.
short is pronounced sh(oh)rt.
short, sort, port, fort, tort, wart
doll is pronounced d(aw)l
doll, fall, stall, tall, hall, call, mall, pall, ball, gall, wall, crawl, small
door is pronounced d(oh)r
door, four, bore, hoar, more, shore, core, tore, roar, snore, pore, chore, store
I hope this helps you.