How Do I Keep Curled Hair More Curled All Day?

Ok, so my hair is quite straight naturally, with a bit of a wave to it. I curl it using straighteners (lol, lack of money to buy curling tongs), but literally, 5 minutes later, all the curls drop out.

Have any of you got any idea on how to keep it more curled, using products you can find in Boots or Superdrug, etc?

Or no products. Just magic?

Thanks ya'll xxxHow Do I Keep Curled Hair More Curled All Day?
A LOT of hair spray.lol.....im not sure though- it's easier to curl your hair when it's naturally more on the wavy/curly side. I curl my little sisters hair and she has the same hair as you and it falls flat too- crimping it is easier....How Do I Keep Curled Hair More Curled All Day?
I just use a load of hairspay
treseme curl activator :) and hairspray!!
i use hairspray, mouse, gel ..... still alternating what i use. im trying to get them to last at least a whole school day as well!!! no such luck so far.... its disappointing b/c by the end of the day your hair looks gross and dead/greasy. i wish my hair was perfect curls. . . i straighten it then curl it to acheive an amazing look. . . but it doesnt look half as hot by the end of the day.
plenty of a good make of hairspray