Most potting mixes have fertilizer already added to them, so you won’t need to worry about feeding your plants for the first three to four months. Once that fertilizer is used up, it’s time to add more. You can use any commercial fertilizer sold for houseplants.
Your choices are really a matter of personal preference. Some fertilizers are powders or liquids that you add to your watering can. Others are time-release pellets you incorporate into the potting mix. Some of these are considered organic, others are not. I’ve used a wide variety of products: liquid concentrates, powders, time-release pellets, fish emulsion—and even my homemade “worm tea” (the diluted run-off from my worm composting bins). It all works fine.
Mix your fertilizers according to the package directions. More is not better—you’ll burn your plants. I’ve found that mixing fertilizer at half-strength and applying it twice as often gives good results. If you notice white minerals accumulating on the plant’s container, run some water through the potting mix to flush out the build-up of fertilizer salts. Be sure to let the pot drain thoroughly afterwards.