While the above node is a halfway decent beginner's guide to bettas; it has some incorrect information.

The fish you take home should: Be moving around in his cup slightly, but not struggling.
Not really true. Bettas will hover and remain almost totally still for hours on end. They either remain right below the surface, or on the bottom, quite frequently. This is *natural* behavior for this species, and in no way a problem.  Lying on its side is a bad sign, but hanging upright in the water is normal.

Not have any white spots anywhere on the body or fins. This could be a fish disease called Ick.
Bettas should not have any RAISED white spots that look like they are added on the body. like someone dipped the fish in salt. *Many* bettas have white spots or patches as a natural part of their coloration.

Not have any fin deterioration
 Some bettas may look like they have torn fins, but in fact carry the natural combtail trait. This is where the rays of the fin protrude beyond the rest. To the untrained eye, it can look like the main fin has torn in and the rays alone remain. This is a genetic trait actually specifically bred for, along with doubletail, halfmoon, and fantail. These are normal. Some bettas will also bite their own tails, like some humans bite their nails, and this does not indicate infection However, if the fins have any white "fuzzy" areas, or red areas, this is a sign of infection and should be treated.

A fish bowl or small tank. Tip: "Betta-hexes" or "Aqua Babies" are a bit to small to house a happy fish. You want to be able to add a plant without crowding. ½ to 2 gallons is sufficient.
Bettas PREFER a larger tank, of course. A half gallon, however, is sufficient.  Do avoid the tiny tanks mentioned above. If you must use a tiny tank (under 1/2 gallon), change the water completely every 2-3 days, at the least.  With a half gallon, you can get away with one change a week.

A plastic plant. Tip: Bettas like to have a place to play and hide. Real plants are more work, more expensive and most require a supplemented iron source to survive. These supplements can harm some fish despite what the label tells you.
The newer silk plants are better. They look more realistic, move more genuinely, and  most importantly are less likely to become brittle and cut the fish.I have never heard of iron harming bettas, or any other fish.

Betta Food. Tip: Betta like freeze dried red grubs, which are considered their staple. They prefer these over flaked food. They like freeze dried tubifex worms also. A small package of red grubs should be enough to last you a long time.
  Doyou mean bloodworms when you say 'red grub'? Bloodworms--frozen or freeze-dried--are a betta's preferred food, but they take flake *happily*. Many bettas will refuse tubifex worm cubes, but love live tubifex or blackworms. (if you feed any freezedried, be VERY careful not to overfeed; they are higher in fat and protien than the flakes.) After bloodworms, the most common 'betta' food is small pellets.  (Hikari Betta Bio-Gold is by far the best brand on the market.)  Most fish love the pellets, but some REFUSE them. If your betta won't eat pellets and never has, try flake.  If he suddenly starts refusing pellets, your pellets are probably stale. Replace them.

Rinse the tank, gravel and plant thoroughly with water. Tap water is fine. For the gravel you may want to use a strainer. DO NOT clean them with soap.
Use hot water when cleaning, to kill anything that may be on the tank, etc. As stated, absolutely never use soap.  If you have to disinfect, use isopropyl alcohol or peroxide.

If you're using tap water it's a good idea, but not essential, to have the water for the fish sit out for a few days prior to buying the fish to let it settle. Otherwise, your water is fine.
CHECK with your city to see if they use chlorine, or chloramine, in the water.  If they use chlorine, you should let your water sit out at least 24 hours if you don't use a dechlorinator drop.  If they use chloramine you MUST use a commercial product to remove it. It does not gas off, even after days or weeks.  Bottled tap water or spring water (not distilled) is also acceptable.

Dump the gravel in and "plant" the plant. Make it all look the way you want, so you don't have to stick your hands in more than you need to. The water should be about 2 inches from the top of the tank, as these fish can jump.
Do gravel and the plant *first*, then pour the water in down the side or down a spoon or something to make it pour smoothly. This minimizes wet hands and shuffling in the water. and for heaven's sake get a tank with a lid.

Feeding: Feed him 2 or 3 times a day. Feed him enough food so that it takes him about 3 minutes to eat it all. Use your judgement.
feed bettas (and most tropicals) ONCE a day, only what will be eaten in 2-3 minutes. overfeeding is a leading cause of death and disease. proper amount a day = ONE of: three/four bloodworms; three/four pellets; one/two flakes. they don't need nearly as much food as you think. but they'll eat more anyways. Their stomachs are about the size of their eyes.

Tank Maintenance: It is a good idea to change half the tank's water every 7 to 10 days. Make sure to use the water conditioner each time. This keeps the water from becomming stagnant or building up in wastes from the fish. If you do this often you will have to do a full clean up less often. A full clean-up is when you take the fish out (you can just scoop him into a cup) and rinse everything thoroughly and scrub off any grime. DO NOT use soap. You should not have an algae problem if you clean-up every 2-4 weeks.
if the tank's under a gallon, change ALL the water every time. (unless it has a filter of some sort.) if it's over a gallon, get a bloody filter, you'll be happier. if you have a hex or small cup, change every 2-3 days.  An unfiltered bowl 1/2 gallon or larger can be changed once a week. 

Bettas do NOT need friends. They are an independent dweller, and are not lonely. If you buy another fish, the Betta will most likely attack it and attempt to kill it. Even a snail to keep the tank clean is sometimes a problem. The Betta may eat the snails antennae.
Acutally, bettas are only truely hostile towards males of their own species. (Most petstore bettas are male. They're the pretty ones. Females are generally bought ONLY for breeding.) They make *excellent* community tank fish, and are more likely to *be* picked on than pick on others. The barb family, some tetras (not many), and some gouramis, will nip the long flowing fins of the betta. A betta may *chase* some small fish but will generally not harm them.  For a filtered, but unheated tank or bowl, white clouds or danios make excellent tankmates.

Not everyone who works in a pet shop is an expert.
Halleluja! be *especially* wary of generic pet stores like petco and petsmart, their fish staff usually *isn't*. also be careful of *some*--but by no means all--really small fish stores, as many of the shoddier ones tend to be highly unethical and fairly underqualified. They're the ones that will order you *anything* no matter how illegal or impractical, if they can get the sale... (i know some WONDERFUl small stores. but i also know some very shady ones. The larger, longerlived larger fish stores are usually more qualified, emplyeewise. they can *choose* who they hire instead of take anyone they can get.)

If the fish jumps out: Put him back in the tank. Hopefully he is still alive. Bettas have a special organ to allow them to breathe atmospheric air.
Being in the air and breathing it won't kill a betta because of their labyrinth organ. Only dehydration (or the cat) will. Please put him in and hope for the best. and watch out for secondary infections.