The best ways to grow your plant rely on your ability to analyze the needs of your plant. In most cases, this means making sure that it has the right amounts of sunlight and water, as well as fertilizer if appropriate. There are a few tips that are less specialized that can help your plant ward off disease and can help you prevent serious issues that can stunt the growth of your plant, regardless of what species it is.
Air Circulation and Light
Plants need plenty of air circulation regardless of whether they are shade or sun-loving plants. When plants grow lushly or are planted close together, they can end up creating a humid environment for themselves in which air does not flow. To combat this, make sure that you plant seedlings far enough apart that they will have room to grow, and thin existing plants out so that their growth is not so dense as to prevent air circulation. In trees and larger shrubs, thin the plants so that sunlight can reach all areas in the interior of the plant. Houseplants should be placed in rooms with good air circulation and not shut up in a room with no air movement.
Your plant definitely needs water to grow, but too-frequent watering can lead to mold, mildew and disease. In most cases, you should water plants when the soil around them is dry, and not before. Also, water early in the morning rather than in the afternoon or multiple times throughout the day, doing your best to keep the moisture off the leaves to prevent fungal infections. When you water, water deeply (but without creating a mud-hole) so that your plant does not learn to only "drink" from the very top level of the soil, which can lead to problems during droughts.
Monitor and Treat Disease
Over the course of a plant's lifetime, it is likely to pick up a disease or infection at some point in time. The signs of disease are frequently spots on leaves or flowers, or defoliation. Watch your plant for signs of infection--discoloration, mushy areas on the stem or wilting--and use sterile pruning to remove infected parts of the plant. A plant can usually fight off an infection if the diseased portions of the plant are removed and disposed of in a timely manner. If you spot bugs or other pests on your plant, remove them immediately via pesticide or green method to keep them from weakening your plant's health.