With the Zika issues, Consumer Reports did an analysis of repellents that shows the products with picaridin or deet most effective. Other sites and studies show deet as best.
Deet has bee around for years. I go to Walmart and buy whatever has the highest percentage of Deet. My wife has to fool around with dryer sheets or skin lotion. She gets bit, I don't. The trick is to put it on before you go outside.
When we head south, we have a problem with "no-see-ums". They are small enough to fit through the screen wire. I read once about a product to spray on the screens to keep them out but I've forgotten the name and can't find anything in the stores that claims to do this. Anyone heard of it?