Well you see, I'm a highschooler, so money is pretty hard to come by for me personally, so what rick said is true, if you can afford to buy bricks repeatedly (granted, a Bike brick is $15 at Costco). I bought a brick of Tally's almost 5 months back now and still have 9 unopened packs and 3 in great condition. However, I like to keep my magic performing cards in prime condition, and also wish to keep them protected since a few packs are being kicked around in my bag all day. I use a card clip on the deck that I am carrying around to perform whenever. I also sometimes "repressurize" the cards to put them in better condition.
The best thing I can say is first break them in. I find decks that are broken in to last so much longer, even if it's just because I'm not dropping hem in the middle of my performances. Next, use a card clip I am so glad I put m decks in a card clip, just because of how much they get tossed around, or dropped. Finally, keep your older decks to use for other things, so you aren't wearing out the nice ones (you can use them to practice, play games, and just mess around).
Also, make sure you wash your hands before practicing and/or performing whenever possible, so that the finish stays perfect on the cards.