Mosquitoes find their prey using three senses:
First by CO2, as mammals will be releasing it in big quantities (though they also bite reptiles).
Second, by body smell, which as others here have mentioned, diet and genetics may dictate how it is affected.
Third by shape (that's when they are already there) and are trying to figure out where to stick it.
The first one is hard to fix, so for the second I'll recommend icaridin or, if not available DEET, and in gel form not spray. DEET can be a skin irritant, hence why is less preferred.
Spray though is sometimes used when applying it to clothing, as it also may have your smell attached to it.
For the third one, I haven't seen conclusive data but a lot of observational studies: from wearing light-colored ample clothing that doesn't define the limbs to (I guess) wearing stripes like a zebra.