When planting Calibrachoa I often give the plants a slight trim, using a sharp pair of scissors or pruning shears. While not a necessary step, it will increase branching and may help your plants look even fuller.
Calibrachoas are usually the easiest to grow in containers. If the roots are kept too wet it can lead to root rot diseases. In containers, allow the top of the soil to dry before watering again. If your plant is wilting even though the soil is still damp you likely have a root rot problem.
Photos courtesy of Proven Winners