Make sure you read the FAQs completely. There is a lot of trust that needs to be there between the renter and the DVC owner. You can't cancel out and expect a full refund. You need to rent your points with plenty of lead time. If you want to go during busy times - holidays, summers, etc - you need to start looking as early as one year ahead of time.
You get the best bang for you buck by using points at DVC resorts. A code and cash will usually do better for the non-DVC resorts. But DVC resorts are the best - laundry facilities (some in your room) , multiple rooms, either kitchens or kitchenettes.
A studio or one bedroom will sleep 4 plus one child under the age of three. A two bedroom will sleep 8 plus one child under the age of three. A Grand Villa (hard to get) sleeps 12 plus one child under three.
Sunday through Thursdays require fewer points than Friday and Saturday nights, but if you average them out over the full trip, it's still a good deal.