How can I prevent a cramp?

The muscle in the arch of my foot feels really tight and if I curl my foot over I can feel that I’m about to get a cramp, I have to quickly straighten out my foot so as not to feel the extreme pain. Is there a way I can make this go away? I can also tell when I’m about to get a cramp in my thigh, I can feel it coming and unless I wriggle around I’ll get one, and even if I do if I accidentally move back into that position I will get one then. Is there a way I can prevent to onset of a cramp?