Discus are not very hard to keep but let's make one thing very clear up front.
88*F to 90*F is WAY to hot. 84*F is a good temperature for Discus.
The other thing you must NOT do is buy them from a Petco or other chain. Even buying Discus from a fish shop is not a good way to begin. The exception to that would if you know a shop that happens to breed discus in their back room you can go with them.
I highly recommend buying your discus from a sponsor listed at
www.simplydiscus.com.
You may be assured of getting very good stock from anyone of them. Choose a supplier that is near you if possible but do not be afraid to order from anyone who has the fish you want. Never skimp on quality when it comes to buying your stock. Discus live to be older than ten years. You may as well buy exactly what you like the first time even if it means paying overnight freight. If you go on the cheap with your stock you are throwing your money away.
Young Discus should be fed four times a day. Tetra Color granules, frozen Blood worms, frozen beef heart blends are all that they need for getting good growth and color. They also appreciate live black worms and live brine shrimp for an occasional treat.
Starting out with discus 3 inches is is better for first time discus keepers. Discus at 2 inches are still best left to those with experience. Discus aren't manufactured so you can expect them to vary a little from the nominal size listed.
The idea of raising discus in bare bottom tanks is founded on the idea that bare bottom aquariums are much easier to keep clean. Unfortunately they are also ugly tanks to have in your living room. Fortunately there is a middle ground that retains ease of maintenance with improved aesthetics. A very attractive grow out tank can be designed. I never use bare bottom tanks because they are to ugly and I am a discus breeder.
It is OK to use a thin layer of sand no more than 1/4 inch thick. This is just as easy to keep clean as a bare tank. You can add some attractive pieces of drift wood; I happen to use that Malaysian wood in my tanks. All you need to do is give it a good rinsing in hot running water before placing it in the aquarium. Discus like plants. You should grow one of the floating plants and allow them to cover about half of the surface. Discus like the shaded areas at times. Any of these floating plants are very good. Water Sprite, Tropical Hornwor,t Ceratophyllum submersum or Riccia fluitans are all good choices. Additionally rooted plant may be potted in those Glad ware food containers. Good rooted plants for a discus tank are Echinodorus species, the Amazon Sword Plants. The best species of Sword plants are E. bleheri, E. amazonicus, E. parviflorus var. "Tropica" and the various Hybrids Swords like Ozelot and Kleiner Bar do very well with only moderate lighting, 1-1/2 to 2 watts per gallon is sufficient. The potted sword plants only need a fertilizer in the pot. No liquid fertilizers are necessary nor CO2. I highly recommend RedSea FloraBase as both the potting soil and the thin bottom layer.
Here is a look into one of my Red Turquoise grow out tanks using FloraBase. These are 8 week old discus and the small plecos are some of my baby Peckoltia sp L134 Leopard frog. There are a few baby Royal Farlowella in with these, too. This tank is not decorated since it is a breeding room grow out tank. There is nothing wrong to also keep some Rummy Nose Tetras, Cardinal Tetra or Pencil fish with your young discus.
I recommend including one common Bushy nose Pleco as the algae eater and if you wish, Corydoras sterbai are one of the best and prettiest Corydoras species suited for warm discus aquariums.