Hair Problems. please help?

i wanna start straightening and curling my hair now cause when i scrunch my hair it doesn't come out as good as it should and my family is starting to say i should do something with my hair and ive seen girls who do it everyday but im woried tht all the heat will ruin my hair and especially when i get older unless i can deep condition it every once in a while or cut my hair? should i do it cuz im kinda sick of having frizzy poofy curly hair thatt is unmanageable. by the way i also wanted to know a good deep conditioner tht is cheap, works, and isnt a hassle. some tips would be great ^_^ thanks