Wooden features can add some diversity to your trails. Whether a little bridge over a ditch or a drop over a cactus, wooden features are fun and challenging. (To ride and to make.)
We don't bury our wooden jumps in the dirt because that would cause the wood to rot. Instead, we level the dirt in the area we are going to put the jump and pack in the dirt around the ramp. This keeps the jump from rotting and blowing over in strong winds, but you can still pick up and move the jump easily.
If you want to make a jump out of dirt but don't have a lot, then just make it shorter and add more lip to the takeoff. You don't even have to build a landing if you are really low on dirt.
If you are more of the cross county type, then building your trail will be a lot easier because you do not have to build all of the wood things and dirt jumps. All you have to do is add a bench cut here and there, which is fairly easy.
If your yard has lots of steep hills and traverses, then you could make a trail that sweeps through the canyon walls. Also, if you like to jump (like I do), then you could add a hip jump on the side of the hill. For a hip jump the landing has to be at a different angle then the takeoff, which forces you to do a small turn in the air.
What kind of awesome features will you build in your yard?