Brass may be metal but it is a soft metal, and dings, dents, and other seemingly minor damage to your saxophone will not seem so minor when it affects the tone and results in expensive repair.
Always store your instrument in its case (one that is dedicated to carry a sax) to avoid having it knocked over or being damaged by anything falling on it. When you are playing, keep your case next to you if you can, so that if you have to put the sax down, you are putting it in a protected place.
When you purchase the instrument, have the salesperson show you how to properly place the sax and all of its parts in the case. Always keep the parts in their dedicated spaces. When you pick it up or put it in the case, do not do it with the neck or keys.
If you are going to place the saxophone in long term storage, keep it in a climate-controlled environment after having performed the proper maintenance it requires. Make sure that it is clean and dry, using cotton swabs to carefully ensure that small parts like the mouthpiece are free of moisture. The environment in which it is stored should be low humidity and moderate temperature.