To move the plant outside, choose an area in your garden that drains well with full sun or partial shade. Dig a hole that is twice the size of your root ball, and plant it at the same depth that it was planted in the pot. Replace the soil around the plant. You may want to spread an inch or two of mulch around the plant. Coleus plants can be planted about one foot apart from each other. The more sun coleus receives, the more vibrant its colors will be. If possible, expose your coleus to sun all morning and shade in the afternoon. Otherwise, keep your coleus in partial shade.  If your coleus is dropping leaves, it probably needs more sun. USDA Hardiness zones vary slightly by species and variety, but most coleus plants thrive in zones 9–10, if they are kept indoors in winter and outdoors the rest of the year. Coleus plants require constant moist soil, but will rot if left in puddles. In very hot or windy conditions, you may need to water daily or even twice daily to keep the soil moist. Increase the amount of watering if you notice wilting, dry brown spots, or fading color. Water the soil directly, since wet leaves are vulnerable to disease. If you want to speed up the plant's growth, use a general purpose fertilizer such as a 10-10-10 solution. Fertilizer can promote straggly or weak growth, so use one of the following options to keep it to beneficial levels:  Apply a timed-release fertilizer according to instructions, just once each growing season.   Or dilute a liquid fertilizer to ½ or ¼ strength, and apply once every 2 weeks. Removing some of the plant's branches is recommended to prevent the coleus becoming top-heavy, and in order to shape it attractively. Here are the basic pruning strategies commonly used for coleus:  To encourage coleus to grow straight, pinch off the side branches, but not the leaves growing directly on the stem. Do this if you want a more "treelike" appearance, instead of a wide bush.  Once the coleus has reached the desired height, pinch off the top center shoot on the plant, to encourage it to fill out and become bushy. Remove flowers from the plants as soon as they appear, so the plant focuses on growing strong roots and thick foliage instead of creating seeds. If you enjoy the flowers, consider removing most of them and leaving the ones in the most visible locations. If the plant becomes top-heavy or leans in one direction, tie it loosely to a gardening stake using twine or another soft material. Ideally, do this during repotting to minimize the number of times you handle the plant. You can also prevent indoor plants from leaning by regularly adjusting which side of the plant is exposed to the light.

Summary:
Transplant the coleus outside. Decide on a sunlight level. Keep the soil moist, but not soggy. Fertilize (optional). Prune the coleus. Pinch off flowers. Stake the plant if necessary.