If most of your perennial flowers get tall and leggy, it may be an indication that your garden has too much shade or is receiving too much nitrogen fertilizer. Either situation can cause tall, leggy growth in perennials. Use fertilizer with lower nitrogen content, or grow more shade-tolerant perennials if your garden is shady. You could also grow dwarf versions of your favorite perennials to eliminate the need for staking.
If you must stake, get the staking in place early in the season, when new growth is just beginning. This allows plants to grow up through the supports, hiding the stakes by the time the plant is in bloom. There are several types of stakes from which to choose. Single stakes are best for long-stemmed plants with large, heavy flowers, such as delphiniums, dahlias, and lilies. Tie the flower stalk to the stake as the stem elongates. Make sure the tie is loose enough so that the stem can move a bit. Use soft twine or garden twist ties that blend in with the foliage, and make a loose figure-eight loop around the plant stem and stake.
Twiggy branches pruned from trees or shrubs can be used as pea staking. Insert the branches into the ground around the edges of the clump. Large clumps may need a few pea stakes in the center as well. Cut the branches 6-8 inches shorter than the perennial's mature height so the staking will eventually be completely hidden.
You can also create a staking framework from bamboo stakes and twine. Place bamboo stakes in a circle along the edges of the perennial clump. Weave twine from one stake to another on the opposite side of the clump until you've connected all the stakes in a grid pattern. Place stakes before the plants begin to flop open. Keep the woven grid below the height of the mature foliage so it will be hidden from view. Bushy perennials such as peonies can be supported with circular metal rings. Many garden centers carry peony rings and tomato cages that can be used for this purpose. The perennial foliage will grow and fill in to conceal the ring.