I don't think you ever get rid of them. I think you learn to deal with them. You can get the traps but it is usually recommended to give them to your neighbors instead of using them yourself. The scent will attract them from a long way and if they happen to pass your garden on the way to the trap, they will stop and have a feast. If you have a fairly consistent wind direction, you could try putting the trap a fair distance downwind from your garden to trap the ones that are attracted by the smell of your garden. You will catch a whole lot of Japanese beetles with the traps but I'm not sure how much good they actually do you. If they are well positioned, probably some.
What I do is take a large yogurt cup, put a few drops of dishwashing liquid in it, then put a couple of inches of water, then collect the beetles in there. The dishwashing soap breaks the surface tension so they drown quickly. If you do straight water, they can still be swimming in there the next day. They seem to naturally fall down when you disturb them so hold the cup under them and a lot of them will just fall straight in when you try to grab them. I use more of a shaking and scraping technique than a grabbing technique.
Good luck!
Editted to change it to downwind from your garden. You want the trap to intercept the ones that have smelled your garden before they get there and the smell will travel on the wind. I still think the traps probably do more harm than good. I think they attract more to within smelling distance of your garden than they catch.