When I'm outside and want to keep mosquitoes away I will use an oscillating fan on me.
The oscillating fan helps to create wind which the mosquitoes cannot fly around in so they fly into the wind and then they fly away.
The fan does not kill the mosquitoes but it does keep the mosquitoes away.
You can also use some mosquito spray that is made to spray on your clothes and skin to keep the mosquitoes away or use Citronella Candles.
Getting one of those good propane operated mosquito magnets also helps as they suck in the mosquitoes and kills them.
The Mosquito magnets are not cheap but they are well worth it and I have 2 set outside my house and the propane tanks last around a month in them and they kill a lot of mosquitoes.