it depends for the budgie and cockatiel (wich isnt my birds but i hang out with them frequently) i use millet spray (bird crack) with the amazon that is slightly bigger and slighlty more motivated by food it seems, I either use fresh fruit, I know he goes crazy about red peppers (not the hot ones, although I hear you can actually feed your birds these) and if he didnt get red peppers in his fruitbowl a day I can easily motivate him with it as treats, sometimes i go for small peices of peanuts or safflower (dunno if thats the correct spelling/name) seeds, or banana, the banana is great for getting him todo something I know he is unconftible with, couse he really goes crazy over it, and that he never gets except as treats, a messy treat tho and there is banan smudge to clean up everywhere when doing recalls or something

oh small peices of appels seems to motivate him a lot as well. just place 5 of each possible treat on a trey or something and see wich one runs out first, should give you an idea about his favorite.
But basicly patience will help you the most, dont expect your new bird to be stepping up within a week or two, some birds are more curagious than others. Some birds that stepped up for their previous owner wont step up when relocated and you will need to build the trust before it does...