Every general contractor has a network of trusted sub-contractors. That allows the "general" to gather accurate bids quickly. If you act as your own general contractor, accomplishing the same thing will require quite a bit more time and effort.

Consider the following:

• For every specialty (electrical, plumbing, etc.), you'll want to get multiple bids.
• For each of those bids, you'll need to walk the specialty contractor through the project and answer their questions. If one contractor shows you a different way of doing something, you'll need to communicate that to all the other contractors and have them re-bid the job so that all the estimates are alike.
• And finally, you'll need to compare and contrast the products and techniques used by each contractor to determine if all are of equal quality.