garage sale GT said:set the seat so your feet can easily reach the ground.
when you start to lean over, steer into it gently. Or to put it another way, turn in the direction you are leaning over.
Whatever you do, don't buy a cruiser bike with coaster brakes because then you can't learn with your feet outstretched. you will have to put your foot on the pedals to stop.
garage sales are a good place to pick up a cheap bike; just get one with hand brakes.
Gee, I was going to say just the opposite -- I recommend that you start with a sub-$100 "beach cruiser" with a coaster brake ... a hand brake (as a supplement) would't hurt, but ...
With a coaster brake:
[center]pedal forward to go forward, reverse direction of the pedals to stop[/center]
EVEN IF you are going to use the hobby-horse method to learn how to sit on the bike & to acclimate yourself with the bike not falling over as you go forward.
STOPPING is as important as moving forward -- with a coaster brake, put your OTHER foot down as you push the coaster brake down & toward the rear of the bike with whichever foot you choose to stop with.
There IS more, but (as suggested) finding a friend who is willing to teach you (who knows HOW to teach you -- not everyone who knows how to ride will be able to teach you) will greatly expedite your learning process ...
BTW. Get a helmet. Wear gloves (any kind, initially), long pants (roll the right pant leg UP if there isn't a chain guard!), etc. No sandals.