The best (non-toxic) repellant I've found for mosquitoes is blasting them away with a low to medium powered box or table fan.

I live less than 1000' from the water's edge, so mosquitoes are ever present for about 9 months of the year. I've tried citronella candles when out BBQing, watching my children play in the lawn, etc. I don't like dousing myself in chemicals, so I don't spray myself with deet, etc. They are a nuisance for which there is little to be done other than avoidance.

Deet is benign to humans. Lots of studies on it since it was invented to protect those building the Panama Canal.

You can also build bat houses. Bats feed almost exclusively on mosquitos. They eat more than their own body weight in them.

There is a great story behind this and I dug deep into the research and history dozens of links long but this might inspire you

https://en.m.wikipedia.org/wiki/Hygieostatic_Bat_Roost

If you can stand the smell, neem oil is very effective. I use low concentrations in a spray bottle, and spray my windows, they generally don't come in..