Ed, you didn't mention what type if any dust collection equipment you own now, or the types of machines you will be running. Bob is on the right track with the solid door idea. If you can't afford to do it right away, then at least buy plastic drop cloth and staple it over the door opening. I would run it a couple feet past on each side.
If you have no dust collection equipment to start with, buy yourself a Shop Vac brand vacuum. The reason I specify this brand is simple; they designed filter bags to catch the bulk of the material and small filter bags to place over the filter inside to stop fine particles from passing through the motor and being blown everywhere. Using this set up makes a big difference. You can hook this to many tools with the large hose. The small hose will conect to the dust port on many miter saws. You can buy a dust catcher for your table saw if it does not have a vacuum attachment. This will help contain the bulk of the large dust and chips. Air filtration is important; no sawdust is good for you, and some is outright toxic.(exotic woods) You can buy one of the air filter units designed for a woodshop or at least get a used HEPA filter from a garage sale. Always wear a dust mask when sanding. You can improve on any of these suggestions at any time without losing out on your investment. It's your health!
"Living in the D" (this means Detroit!)
"It's fine to disagree with other members as long as you respect their opinions"