Like jynx said it helps to know what budget your working with.
Essentials I think are..
(any where from 2.5+ gal depending on how many fish your getting.. with lighted hood)
.. the one I use is whisper and seems to be low flow impact on the fish
50w (if you can afford one with actual temp setting I would get it)
(i would stay away from the beads bc I've had them break and I suspect tore my fishes fins... but its your option)
Vacuum and siphon
(if you get a tank 5+ gal I would think)
(prime works well but is highly concentrated and you would only need a teeny amt for a 2.5 gal (its 1ml of prime for 10 gal))
(if this is your first tank I would def not try to do live plants)
or some other decoration with room to hide in
( i like the glass ones that actually look like thermometers, work well and are cheap
and like the first poster said bloodworms or brineshrimp ( i used freeze dried)
(always useful when filling up your tank)
(to test your ammonia, nitrite, and nitrate levels during your cycle)
thats all I can really think of. Definitely hold on to the cup you buy him in in case you want to take him out to clean, etc.
Good Luck on your new fish and make sure to put up some pics of your set up and new fish when he /she comes home