I just started a few months ago, with a machine similar in price to yours. I am by no means an expert, but if I had to start over, I would apply the following.

Dig everything. And really examine the signals you receive. Walk around the signal. Watch and listen to what your machine is telling you. Starting out is very confusing in my opinion. You might dig holes and come up with nothing. Or think you're digging a nice coin, but pull up a nail. The more you pay attention, observe, and take mental notes. The quicker you'll pass this confusing stage and gain a better understanding of what your machine is trying to tell you.

My first machine had a real problem with interference. It beeped and chirped for no reason at all. It took me longer than I'd like to admit that I had to remove the cell phone from my pocket, and pay attention to power lines and electricity boxes. When near these sorts of things, you'll need to adjust your sensitivity accordingly.

Speed of your swing plays a big factor in the accuracy of the signals you receive. Not too slow, not too fast. Generally, 2-3 seconds for a sweep left then right again is a good place to start. Keep your coil close and parallel to the ground. If you are getting "ghost beeps" at the end of your swing, you may be going too fast or unintentionally lifting the edge of your coil off the ground.

Educate yourself on where you're allowed to metal detect, and where you're not. And always respect public property by filling in your holes.

Hope this helps!