There are several ways. I prefer something I can mix at home and use. Try 10-15 cigarettes crushed into half a gallon of water. Let it stew for a day or so, then strain the water with a coffee filter into a spray bottle. Add a teaspoon of dish soap and then spray the little buggers when you see them. Also you can vacuum them off your plants too. If you do that just toss them in some soapy water and they will parish quickly.
Diatomaceous Earth works on them too. They hard part is finding their little eggs hiding somewhere and you will never find them all. However, I just noticed as I am writing this, there are about 3 hubs on the "related hubs" list addressing this very issue.
Good luck with those stink bugs.