A lot of this is personal preference, some guys like to just pass shoot the birds, that is; get in their flight path and just shoot them as they fly over.
I personally, hunt for the calling, the interaction between me and the animal is what does it for me, so, I set up with decoys, layout blind, and call the birds in.
For geese, I would recommend a 12 gauge, bigger shot generally helps with geese, say 1 shot up to T shot. Choke, well depending upon how far you estimate your shots to be, however a modified is probably your best bet for an all around choke, but you can get fancy with these if you like, picking up some expensive aftermarkets.
Calls, if you decide you would like to go the route of decoying the birds, you can start with a simple flute call if you like, they are easy to run, pretty basic, or go as nuts as you want, including short reeds that can run you $250. A short reed will allow you more versatility, a faster call, easier to get aggressive with, but harder to learn and master. They do make inexpensive short reeds as well, something like an RNT goosezilla, Tim Grounds Poly Super mag (very good inexpensive call)
Decoys: I personally like fullbodies, something like a bigfoot might be perfect for you, they are a tough decoy and not bad on price, but there are many brands out there, GHG hunter series or Pro grades may fit you better, just browse and see what you like. A lot of guys like to have more feeding decoys vs. actives. For example; 8 actives and 16 feeders, it shows a more relaxed flock, hopefully giving the incoming birds more peace of mind.
You can also buy shell decoys, these are not as visible, however are less expensive. I'm personally not a shell guy, I just don't find them to be near as effective as fullbodies, with sleeper shells being the exception.
A flag, this can be a big help as well, a wise purchase, there are many out there, they'll all do the job.
So, if you decide to ambush/pass shoot, just get under their flight path and try your luck. If you would like to get into it a little more and would like to decoy the birds, then go out, find the field they are using, set up exactly where they were the next morning, I'd say 16-24 fullbodies would be a good starting spread, a layout blind and you can look at these, pick one that is comfortable, get your flag ready, call in hand, and get ready to shoot some birds.
If you are where the birds want to be, basic calling will work fine, single clucks, honks, etc... When you first see the birds you can use the flag to get their attention, I'd recommend not using the flag when the birds are within 100 yards, as they will pinpoint your location.
Use the natural vegetation from the field to stubble up your layout blind. I.E. corn stubble, wheat, whatever it may be. Make your blind disappear, it needs to blend in perfectly, or at least this will help immensely when finishing birds close.
Your most common equip: Fullbody decoys will range from $100 for 4 to 6 decoys up to $250 for 6 decoys. Layout blinds are from $100-200 bucks. Flag is 20. Call, to start probably $20-60 bucks.
As you'll see, you can go as nuts as you want, from decoys costing $1000 for 12, to $250 calls, $1600 shotguns, $100 chokes, to buying used decoys, basic calls and so on.
I personally recommend decoying the birds, I believe it to be more rewarding, the calling, the close quarters, when things go right, you may have birds landing feet from you, close enough you hear them weezing, you feel their wingbeats, it's hard to beat.
