What precautions should i take if i am at risk?

It depends: What are you "at risk" for? Learn all you can about that condition. If you're at risk because of a family history, ask family members how they found out they had the condition, and ask them to ask their doctors about screening tests for the condition.

All of them: Sorry, but you need to elaborate as to what you are at risk for to allow an answer. Cancer? Heart disease? Pregnancy? Overexertion? Etc. Need to tell us more.