When you're trying to use a hammer drill safely there are a number of things you can do, but none of them is more important than simply using your brain to assess your situation. If you can spot danger in advance rather than after the problem has occurred, you're almost certainly not going to have any problems. However, if you're just going to relax and spend hours drilling and you don't pay attention when you are doing so, you're just asking for trouble. You could end up with serious risks of injury.
Safety is absolutely vital in any environment, especially when you've got something as potentially life threatening as a hammer drill. You shouldn't just rely on your own strength and intelligence; you should have someone with you at all times to assess the danger. If you can't have that person with you, you need to take your time with the job and understand that there are much worse things than spending twice as long on a project simply because you are worried about safety.
Cordless Drill Driver
It's also absolutely vital you understand what you are going to do if the worse did happen and there was a serious problem. Who are you going to call? Where are you going to go? You should be thinking carefully about all of these things, because the last thing you need is to be left completely isolated without knowing what to do when you've just had a serious accident. Using your hammer drill shouldn't be that much of a risk. One way to reduce risk is by knowing what you are going to do if something was to happen.
You also need to remember to use any appropriate safety guards. A lot of the risk will depend on the type of the material you are hammering with your cordless hammer drill. In general there should always be some safety measures in place on the actual device, rather than simply relying on your own safety measures.
You should be thinking about wearing safety glasses just in case something was to fly off and hit you, but again it's up to you. You aren't going to be able to completely remove all risk, and so you're just going to have to take as much risk as you are comfortable with.
If you aren't happy about something, stop and think about what you are doing. This way you won't regret anything. With patience, it will prevent serious accidents. There is nothing worse than having a serious accident and knowing it would have been prevented without much thought, just a little bit of patience.