Pansies are not difficult to grow. Good soil, steady moisture, and at least partial sun will provide the results you're looking for. What they don't tolerate is heat and humidity, which is why they thrive in spring and fall.
Plant pansies 6 to 8 inches apart. They can be used as borders, or in larger masses, but don't count on a solid ground cover. The plants are more clumping than spreading. Pansies respond well to regular deadheading. As often as possible, every couple of days if you can, pinch off faded blooms and any fruit (small green seed capsules) that may be forming. This will spur plants to continue blooming.
Fertility aids vigorous bloom. If you apply a mild fertilizer at fall planting and every four to five weeks in spring, it will ensure good nutrition for the pansies. Pests are not a major issue with pansies, but slugs and snails do count pansies amount their favorites, so control may be necessary from time to time. Aphids can also crop up occasionally. Leaf diseases, particularly mildews, are fairly common, and the occasional plant will die from root or crown rot, so take care not to bury the stems or crowns. Healthy plants and good growing conditions (ample sun, fertile soil, and good drainage) will keep pest problems to a minimum.
Heat causes pansies to become leggy and lose most of their bloom. So when summer warmth begins to get the upper hand, go ahead and remove pansies to make way for your summer annuals.