Tikka from MB is right on the $ in his assesment.
And I'll assume we are talking about Canada geese, the bigger species such as Giants and the Greaters, VS the Lessors and and such.
Here is the list in importance in goose hunting.
1) Be on the "X" EG be in the same field as they were the day before, as close to exactly where they were.
---if there is a major wind shift-you may have to adjust where you set up though in the same field.
2nd choice is to "run traffick" on them, by setting up between where they are roosting and their feeding feild.
2) Concealment. You have to be well hidden. Layout blinds such as Final Approachs Pro Eliminator or Zinks Finisher work well for mobility of hunting different fields and you are well hid. Each has its + and - for which better suits you. If you need a lot of portability, think the smaller layouts which are compact by same Mnfrs.
Pit blinds work if you are restricted to 1 field, but are costly and generally need to be dug 6 months prior so that the vegitation has a chance to grow around them agin so it looks natural.
I would keep away from the goose chairs.
3) Decoys. Use good or better quality decoys.
Use full bodies such as Big foot and Green Head Gear as they are the best mass produced and hold up well.
If space is a problem (lack of trailer or stoage) use Silos, go with Real Geese Pro series as 1 side has a no glare to it (no reflection of the rising sun-which will spook incoming geese).
Keep away from the 1/2 shells IMHO. If you must use shells, go with the 3/4 body shells such as G&H and buy the magnum sized ones.
Also consider adding movement to about 1 decoy per 6 by added a Decoy Dancer, or swivel base, or similar.
Also important is flagging. Buy a few videos of the Pros and watch how you are flagging.
4) Calling. Calling is important, but often guys over call and flare the geese. It is best to under call than over call. Each day is different, experiment as to what they want to hear. If you buy a call, buy the instruction VIDEO with it, meaning forget the cassete or CDs, get the video because in calling geese, how you hold your hands with the call is very important, so watching it is a big help. Flutes VS Short reeds have 2 completly different ways in how you control the air used in the calling. Both are effective. I know that Zinks SR-1 is one of the easier SRs to learn and comes with a video. On SRs it takes some guys a couple of weeks, some years to become proficent with it--so start now to learn it. Flutes are much easier to learn to call but have limitations in the overall notes it can produce. The very easiest to learn is the Big River flute, but alot of guys use it--but it does have a very low low end sound to it-which makes it suited well for over water hunting conditions and the Giants if the hunting pressure is light. ALso check around where you live to see if there is a Duck and Goose calling Assn. some states have monthly meetings, go to them and abserve and absorb info. And do not be scared off off by the competition callers. Just frankly say you want to learn how to "meat" call, meaning hunting VS competitive calling. If no Calling Assn around, ask some of the hunting retailers in your area if they know of anybody that can help you learn the basics of calling.
Just remember, we all have our opinions and different experiences, and of course the regional hunting varies widely too across the US and CA, meaning there are variables to consider. But the above info I beleive most would consider good sound info.
And to answer your original question, I've shot a lot of geese over 9 full bodies, a mix of feeders and uprights. But as the season progresses and the flocks get bigger, it does take more decoys.