A 12 or 20 gauge repeating shotgun makes a good dove gun.
I took a 20 last year and did fine with it and I didnt get beat to death. But this year I am taking my new 12ga.
As far as ammo goes. Most of us will get the cheapest thing we can find. I usually go through about 6 boxes. For a 12 or 20 gauge, just ride up to wal-mart and buy about 2 of those 4 box packs of Federal, winchester or remington shells for $14.88 a box of 4. Get them in # 8 or 7 /12 shot. (I like 8s, there are more pellets and I dont miss as easy.)
If you shoot at long distances then some 7 1/2s would reach up there a little higher, and you may want to buy a box of hi-brass in 7 1/2 shot for those last minute hi flyers.
A Improved cylinder or modifed choke works fine.
I wear a realtree camo t shirt and pants with non. insulated hiking boots. Just dont wear a bright colored shirt and you will be ok.
If I sit in the middle of a field then I will sometimes put a little blind up, but I dont think its that nessecary.
I also put dove decoys on the ground in front of me but again, you dont need them.
For cleaning, you can do like my dad and pull the head off and pluck and cut down the middle (like you do a fish) and remove guts and then the breast.
I like to pluck the breast feathers and twist the wings around a few times until they break off, and give the head a little twist and tug and it will come off. Next feel for the end of the breast bone, take your thumb and push in at that spot, (you can cut a small hole there if you want, but your thumb will usually bust through the skin.) Get your thumb up under the bone and pull upwards to about a 90 degree angle, this should remove the breast. If not, just cut what you have to to remove it.
Cooking, I like to batter and fry them in a skillet with a little canola oil. Flour or cornmeal works. We also cook them on the grill.
If you will be hunting with other people, then the decoys arent really nessecary because all the people will keep them moving around on the field. Also, if you cripple one just pick it up and knock his head on the gun barrel or hold his head and swing him around in circles, or just pull the head off. Dont be like some people I have seen and shoot them again or shoot at ones 2 miles in the air.
Take plenty of shells in # 8 shot
Gun with a mod. or improved cylinder choke
cooler with water to drink and ice to put birds on
and a seat to sit on, drab clothing and yourself and your ready