For one bearded dragon you will need at LEAST a 55 gallon tank. I would suggest something a little bigger though to allow for a more comfortable living area where they can easily move around. All of my adult cages are at least 4'x2'x2' (some a little bigger).
For substrate I use white, non printed paper towels. Others use childrens play sand, bran, etc. Research all options then choose which one you will feel comfortable with.
You can buy artifical branches, rocks etc for decoration. I personally go out and get river branches and small round river rocks then treat them to make them sterile. I soak them in a bleach solution for 24 hours, then in regular water for another 24, rinsing them well at the end. This kills any parasites, bacteria etc that might be on the items. I use approximately 1/2 cup of bleach to every gallon of water when soaking.
You will need a heat lamp fixture and a uvb/uva flourescent light and fixture. For uvb/uva I use repti-sun 5.0 bulbs and sunlight when I can get them out to bask. For heat you can use a regular household bulb, adjust the wattage so that the temps on the basking side are around 105-110 and 80-83 on the cool side. During the "summer" (approx feb-nov) I leave all the lights on 14 hours a day. The other 10 they are off. During the "winter" (nov-feb) I leave the lights on 10 hours or so and off 14.
You will also need food. For staples you can use crickets, roaches, silkworms along with greens/veggies daily. Greens should include mustard greens, turnip greens, dandelions, collard greens, kale, escarole, endive etc. Vegetables like squash, carrots, peas, green beans etc should also be added to the salad. You can offer superworms and waxworms occasionally to sub adult and adult dragons.
Dont forget supplements. A good calcium supplement and multi vitamin should be used. I use repcal calcium w/ d3 and rep cal herptivite multi vitamin.
Also dont forget to call around for a vet that specializes in reptiles and who has experience with bearded dragons. It is important to get all newly acquired dragons at least a fecal exam. Unfortunately because they are fed live foods they run the risk of parasites which can cause a dragon to go down hill fairly quickly if left untreated.
I have NOT covered everything! I would suggest you read and read
Everyone raises their dragons differently (different substrates, different housing, different lights, different vitamins, food etc). All of us have the same thing in mind though, the care and whats best for our dragon. We have read and decided what we thinks best. I would suggest you do the same 
Goodluck on your new baby! They are a joy.
Take care, Lindsay
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BC Dragons