Orchids are affected by many of the same pests and diseases as other houseplants. Insects such as mealybugs and aphids can be controlled with water rinses and insecticidal soaps.
If you want to buy a potted orchid for yourself or for a gift, check online for local orchid growers or societies, or visit your local florist, greenhouse, or garden store. These can be great sources of information, as is the American Orchid Society (www.aos.org).
If all this culture sounds too much for you or your Valentine recipient, consider a cut-flower orchid you can find at florists. Protect it from cold on the way home, and from cold drafts once home. Keep away from direct sun and heat sources. Cut Cattleya should last for one week. Phalaenopsis, Oncidium, and Paphipedilum should last one to two weeks as cut flowers. Longest lasting orchids as cut flowers, often from 4 to 6 weeks, are Cymbidium orchids.