I have done a few dozen, both dish, direct and two way internet.
You need to be handy, have some knowledge about how a house is constructed, how a commercial building is constructed and the differences. Have a grasp of the local building codes if any. What kind of mounts to use, ground type, roof, non penetrating roof, some knowledge about concrete in the event of a pad install. The Golden Rule of the installer is 'leave it better than it was when you started and do no damage'....
Need hand tools, good power drills and bits for both wood, steel and masonry and a sears sale special won't cut it. All my stuff is millwakee from my 3/8 to 1/2 to my 3/4 hammer drill so there is some bucks involved there in outfitting. Steel snakes for routing pull strings thru walls and ceilings. Ladders, GOOD ONES, rack for the roof to carry. Be aware it is not a good idea to drill thru an outside wall directly opposite of an outlet, can be a shocking experience. Some basic electrical knowledge like don't put the receiver/router on the same ckt as the microwave or refrigerator.
How to hide wires, difference between opening a drywall wall and a plaster wall, 50ft cracks in plaster are expensive to fix if you don't know how to plaster. Good liability insurance costs about $700 a year for a million coverage.
An installer is kind of a jack of all trades. I use it as an opportunity to pick up other business like 'Would you like your rooms cabled for a network while I'm here for an additonal $100 a room for one drop each, 2 for $150. I can also install a router/firewall for your broadband connection and do some maintenance on your win98 PC's while I'm at it.' Some $50 installs I walk away with upwards of $1000 bucks or more when they find out I also build systems and service them locally. I just finished Pocono Raceway today. Started out as a firewall install, finished up with redoing their entire network, workstation upgrades and fixing their win98 and win95 workstations that have been untouched for many years.
I have had customers that have paid me to install shelves, build book cases, replace broken windows, hookup home entertainment surround sound systems, unreal, which is one reason I now carry my Avia DVD and sound meter in my XJ along with all my other tools. Yea, you do the install, why not sell some UPS's for the receivers so they don't fry from voltage surges, buy them at sams for $50 and resell them for $80 'Gee, that new $2000 #ell computer [I build better ones

] should have one too so that a telephone/cable/DSL spike does not fry it'. Depending on the cars in the driveway

I've sold systems when they show me their new acquistion from dell or gateway. Usually commenting that they are OK but some of my customers prefer higher performance systems but that they are quite a bit more expensive than that #ell or *ateway and bingo they are hooked and before you know it I'm buidling a antec tower'd 500watt, 3.2 gig sata ATI or Nvidia screemer for them thats feeding their new HD plasma display.
Don't just limit yourself to doing dish installls, look around and see if anything else need fixing, I do and it pays.
Join your local chamber of commerce, get or print some cards up, I get a lot of local lawyers and doctors plus other small business's that I met thru the chamber. This raceway gig was from a business card exchange, out of the blue. Form a sole proprietor business and get a tax number, costs $50 here in PA, do a $600 corp later on. If you have questions shoot me an email, I was where you are at a year ago, now my nose is above water, barely but I'm not drowning anymore.
I once had a salemen tell me that the hardest thing about selling was getting in the door, well let me tell you, you are already in the door

NOW SELL...