Try to reproduce the conditions it would find in the wild.
Most plants prefer to dry out a little between thorough waterings.
Water from below - stand them in a dish of water until all the water has been taken up. Feed regularly to keep them healthy. Avoid strong heat or chilly draughts. Many houseplants like to be outdoors in summer - check all frosts are over first. Do not buy plants that have been standing in the cold, as they may be frostbitten.