Garbage, trash, and garden debris should be eliminated. Have tight fitting lids for garbage cans. For roof rats, thinning dense vegetation will make the habitat less desirable. Mow your ivy off once a year to the ground. Climbing ivies growing on fences or building should be removed.
Trapping is the safest and easiest method for controlling rats.
The simple snap trap is still very effective. This time of year it is more difficult to trap them. If you were a rat, would you want to substitute bait for fresh fruit. I think not. The expert I talked to said the most important thing about trapping rats is to have lots of patience and keep trying.