There is tons of information out there about companion Planting, as well as trap cropping, and spending some time studying these is more than helpful. This linki is to one of thousands of web sites.

Here is a link that might be useful: ATTRA Companion Planting

I've had success with some like basil & marigolds with tomatoes, lemon balm and verious perennials. I used nasturtiums & dill with cukes and still had bugs. Will continue to interplant flowers to attract beneficials, and other herbs with veggies to "mix it up" and confuse the bugs. I found the lemon balm, though it can be invasive if not controlled, is a good repellant. This year I will also plant pyrethrum (sp?)daisies around the edges of a few garden beds. Stay tuned. . .

Marigolds and Pyrethrum Daisy's are good companions.