When you first set out to design your new patio, you must think about all the reasons you want it and intend to use it. These are the easy things to plan. Easy in the sense that you really know what you'd like to have and how you will like to entertain or have some great looking shade in the yard. But, what you may not be planning for is the prepwork or other type of issues with your particular land plot, city regulations, home-owner's association's guidelines, water issues, etc.
These nagging 'details' can often derail you from the excitement of having your new patio cover designed and put to use as soon as possible. There is really nothing to fret over though, because your contractor can handle all these concerns for you. If you plan on doing this project yourself, and it can be done, then you will simply need to have these matters addressed before you move ahead with building your patio cover.
Briefly, depending upon your climate zone, you will need to take into account your frost line. In the southwest, in the lower elevations, where many of these patio covers are built almost by necessity to be able to enjoy the outdoors with the intense sun, frost line issues are almost a moot point. It does get to freezing in the winter on occasion at night, but the ground is never really in any danger of heaving and such associated with footings. However, it is still a code issue, so you should make sure to pour your footings deep enough to comply. Also, if you have any sprinkler system or are looking to build in a lower elevation area on your property, you should consider water drainage. Where does the water flow and pool? You don't want your covered patio to be flooded out in every rain and you don't want the water to affect the level of your posts over time.
As far as design goes, it is really a matter of personal taste. Some people want their patio covers to be big, bold statements in their yards. In these cases, there is often rock and other masonry products used. They tend to have a more masculine or bolder (boulder too) look about them and will withstand the elements quite well. Wood patio covers are another very attractive option. These usually take the form of a handsome pergola or gazebo. The pergola is the most commonly built patio cover in the DIY plans. They are more simple to construct and lend themselves to customization with climbing vines, lighting and other accessories like misting systems and such to keep your patio cool. Basically, if you can dream it, someone can build it.