Doesn't it have to be "are unfamiliar with"? "If the area is unfamiliar to you" makes sense the other way around.
kk110)If you are unfamiliar to the area, open your eyes for detour signs while driving.
I am not a teacher.
The second half of that sentence is rather unnatural. I would hope that anyone who is driving already has their eyes open!
If you are unfamiliar with the area, keep a look out (or keep an eye out) for detour signs while driving.
Remember - correct capitalisation, punctuation and spacing make posts much easier to read.
For that matter, even if you are familiar with the area, you still watch out for detour signs, if they are such a common occurrence.