The first step in making your brick patio is to set up the area. If you are covering a pre-existent concrete patio and nothing else, you can skip this step. Use tent stakes and string to outline the area you would like you patio to cover. It would be a good idea to have some of the bricks you intend to use handy at this point. To save work and extra headaches later, line up a row of bricks with a thin space in between (popsicle sticks work great). Line them up to the edge of your string. If the bricks with an edge piece at the end do not match up to the string you can move your design area slightly to match. This will save a lot of brick cutting later. Once you have your patio area marked with string, dig the entire area out about four to five inches deep and as level as you can. Extend the excavated area an inch past the string line.
Once you have excavated the area, install a durable plastic edging around any perimeter area (directly beneath your marking lines) that does not come into contact with a rigid surface. Use tent nails to anchor the edging into the ground and make sure that the top of the edging is even with the surrounding ground level. Place a few stakes on the inside edge of the edging for extra support. Using string and a line level, run several strings across the excavated area by attaching them to the support stakes. Attach the strings at a height such that if you were to place a brick on top of it, the top edge of the brick would be even with the top of the edging. Make sure that the strings are level and attach them as tight as possible.
The next step is to prepare your under layment. Your patio will settle with time, especially if placed directly onto the soil. You can use concrete, lime or sand for an effective under layment, but I have found that lime provides the best results and is the cheapest. Fill the excavated area with lime until it is roughly even with your string. Even it out with a metal rake and then compact it. You can use something as simple as a cinder block to pound the lime into a hardened layer, or for best results rent a compactor. You will have to repeat this step several times as the lime compacts very tightly and will sink each time you use the compactor. To level the under layment, cut a length of 2x4 the length of your patio. Attach a level to the top center of it and slowly push it along making sure that it is level and even out the lime.
Once you have a hardened and level under layment, begin placing your bricks. Place the edge brick along the sturdiest side (if one or more sides of your patio connect directly to the side of the house). Place a few rows of interlocking bricks afterwards and then check to make sure they are level. Pound each brick a couple of times with a rubber mallet to be sure that they are tightly in place. They may sink slightly or seem a little uneven after this. Small adjustments can be made by adding lime underneath the brick and hitting it with the mallet again. Continue this process until you have used all of the full bricks you can. In areas where partial bricks are needed, you can make cuts in two ways. For straight cuts you can simply use a mason chisel to score and then cut. To do this, measure the brick that needs to be cut and make a pencil line. Place the chisel at a 45 degree or smaller angle with only the corner touching the brick. Using light taps, hit the chisel with a hammer and chip out small amounts of brick along your marked line. Once you have chipped out a quarter of an inch or more, place the full face of the chisel into the groove. With one hard hit of the hammer the brick should crack right along the score line. For complex and cleaner cuts you can rent a Wet Saw with a masonry blade and use it to cut the brick to fit.
Now that all of your bricks are in place you will want to recheck to make sure all the bricks are level. If any of them are not you can add or remove lime from underneath until they are. Once everything is level and even, spread sand over the entire patio area. The sand will fill in the gaps between the bricks to keep them from grinding against one another, and will also give a more finished appearance. Use a push broom to spread the sand around and allow it to fit into all of the seams. You may have to repeat this several times as some of the seams could be very tight. When this is complete, simply hose of the area and admire your new patio.