Diluting oils in a carrier oil is an excellent way to minimize a sensitivity to the oils, some oils are stronger than others and it may only take a drop of oil to obtain the desired effect, by using a carrier it may make the oil go much farther. The oils by themselves evaporate very quickly, by also incorporating a carrier oil it slows down the evaporation, giving the body more time to absorb and in some cases expedite the therapeutic desired effect.
It is recommended that you avoid applying an oil that is photosensitive to an area that will be exposed to the sun as they may cause burning, similar to a sunburn. Here is a list of the ones with photosensitive oils in them:
doTERRA Island Mint®
doTERRA On Guard®
Slim & Sassy®
Please let me know if there are any questions that you may have!