Prepare the soil
Roses require rich and loamy soil. When choosing a spot to plant new roses pick one that gets at least six hours of sunshine a day. Roses don't like their feet wet so stay away from areas that don't drain well. Dig a hole twice as deep and wide as your rose bush container. Backfill the hole with a mixture of 50% compost and 50% of the soil you've removed. Sprinkle in slow release fertilizer per the package directions. Please the rose in the prepared hole. Make sure the soil line on the rose is at the same level as the soil line in your garden. You may have to fill the hole a little more or remove a bit of soil. When you're satisfied, place the bush in the hole and fill the hole half way and water well. When the water has drained completely fill in the hole.
If your roses are already established freshen up their soil by adding compost, well rotten manure, or top soil. Sprinkle with a slow release fertilizer and work this mixture into the soil around the rose bushes.
Bugs and other critters
Keep ahead of bugs by inspecting the roses on a daily basis or at least twice a week. If you catch problems early they won't become serious. Aphids love roses. Wash them off with a hard spray from your garden hose. If that doesn't work use a spray of 1 teaspoon of dishwashing liquid in a gallon of water. The soap sticks to the aphids and kills them but it won't hurt the roses.
If you find a grayish to white film on the leaves and rose buds it's probably powdery mildew. It's not serious but it will ruin the look of the flowers. Use a fungicide especially for roses. Neem is a good one.
Other problems are dark spots on the leaves, holes, skeletonized leaves and flower buds becoming brownish. Take a sample of the rose bush to your local plant nursery and they can tell you exactly what the problem is and how to solve it.