When the water is nice and colored, use it undiluted as an occasional food, or dilute for every day watering. On the other hand, most plants don't want wet feet, and they'll cheerfully die if overwatered. If you use catch saucers under your pots, make sure there isn't standing water in them. If your plants are outside, this will also prevent your saucers from becoming mosquito pools. There are numerous commercial plant foods available.
Light is as critical to container plants as to any others.
Most plants prefer full sun, but those that need some shade will pout if they don't get it. Fortunately, containers are portable. Take your plants to just the right light. If you have to choose between skipping morning or afternoon light, most plants do okay in morning light, while many can find afternoon light too intense. Of course, it depends on the plant.