Does anyone have any advise on how to get my hair to have beach waves?

I have seriously straight thin hair my hair isn't that thin but its not very thick either. the only thing ive done is put it in braids over night then wake up with cute waves but they only last for a couple of hours even with hairspray or gel.Does anyone have any advise on how to get my hair to have beach waves?
With straight hair, the hold never lasts all day (regardless of what products advertise). The best thing to do is retouching your hair throughout the day. Sunsilk has a product out that is a salt spray that gives you beachy waves. you apply it to your damp hair. I have used it and it works for me! Also use a flexible hold hairspray. You want it to look natural!