Insect repellents like OFF Deep Woods, or anything with DEET, are effective. If there’s no wind, you can also try setting up an oscillating fan to blow on your outside sitting area to help keep them away.
Bug spray and/or long clothing that conceals the skin are your best bets.
If you’re looking for a mosquito repellent “device”, I’ve tried them all, and Thermacell is the only one that’s worked for me. We have the portable version and the lantern and they work wonders. My wife who is a self-proclaimed “mosquito magnet” won’t sit outside without them if it’s bad out.
We stock up on refills when they are on sale since they can be a little pricey.