Replacing or repairing a roof is a daunting task for even the most skilled home handyman, but that doesn't mean you have to call the roofing company immediately. If you feel that you're qualified to take on the task yourself there's no harm in attempting the job on your own and saving the money to hire a professional roofer. However, you may soon find that the toughest part of the entire job is getting the heavy material up to the roof in the first place, something that can be solved in a number of ways.
Obviously the cheapest but also the most physically taxing method is simply carrying the roofing materials by hand onto the roof. This is not a problem for basic materials such as nails and so forth, but for shingles it quickly becomes a major chore. While they may not look it, a bundle of shingles is extremely heavy. You may be able to sling a bundle over your shoulder and safely climb and extension ladder onto the roof, but soon your shoulder will be protesting and chances are you'll be looking for a new method. If you feel that you're up to the task, most hardware stores sell shoulder-mounted sling bags designed to distribute the weight of a load of shingles more evenly.
You also may opt for carrying up smaller stacks of shingles each time. A heavy load will easily throw off your balance on a tall ladder, and it's much smarter to take more trips instead of trying to transport everything at once and hurting yourself.
Often you'll see some roofing companies make use of a winch-operated platform. These are also available at most machinery supply stores and greatly enhance your ability to transport heavy materials to the roof with minimal physical work. The assembly features a winch motor that drives a platform up and down the extension ladder that it can easily be installed on. The platform moves up and down via a heavy rope that wraps the length of the ladder and provides movement via pulleys. Most assemblies are designed to hoist hundreds of pounds, making it ideal for lifting stacks of shingles much quicker than by hand.
This method is almost exclusively reserved for more professional roofing operations, but some searching around town may lead you to one for rent on larger jobs. Essentially, this system is one where a conveyer belt on a rigid platform extends directly from a truck up to the roof. One man stays in the truck loading shingles onto the belt while another is stationed on the roof offloading the supplies as they are carried up by the moving belt. Obviously this system requires a great deal of machinery already installed on a truck, therefore it is far less practical for a quick roofing job done by yourself.