Depending on what you learn from your home energy audit, you may be able to save a significant amount of energy through a combination of DIY creativity and craftiness. If your doors and windows leak air, you may not be able to afford to replace them. But making or buying draft stoppers and sealing your windows can at least reduce the amount of energy you lose [sources: Efficient Windows Collaborative, Howard]. Likewise, you may be able to fix air leaks around electrical outlets and switches with handheld sealing tools and expandable sealant, without hiring a contractor to do the work.
The amount of work you can do yourself depends largely on your home-improvement skills, as with any home-improvement project. If you can install cabinets or build a deck, it's likely you can make a large number of eco-friendly improvements by yourself.