There are a number of aspects you need to train for shooting a gun. The specific scenario you are training for will change your choice of gear and approach. I have trained a number of people for defensive style shooting, such as that found in IDPA or IPSC competitions, or for concealed carry purposes. For indoor training, I use SIRT pistols from Next Level Training (http://nextleveltraining.com). With the SIRT pistol, you can practice almost all aspects of pistol craft except recoil management. All of the recoil simulators I have seen have not done an adequate job of simulating any real recoil, so I have stopped considering recoil as something I need to train with. I use the SIRTs and various targets to train things like:
- Trigger mechanics (finger placement, follow through, finding reset)
- Proper eye focus on the front sight
- Target identification
- Shot placement
- Safe and effective draw mechanics
- Basic malfunction drills (Needs to be combined with time on a real gun)
- Safe movement with a pistol
There is a lot more you can do with it. If you combine with the LASR software, you can have your shots scored with a web cam pointed at a target and get very good feedback as well as a lot of fun. http://lasrapp.com
You can do rifle with the AR-15 SIRT bolt option.
The advantages of the SIRT option over the LaserLyte or similar options that convert your real gun into a laser simulator is safety and convenience. The SIRT gun cannot fire a real bullet. The magazines are weighted to feel like loaded magazines but there is no need for real bullets anywhere in your training area. The RT part of SIRT stand for "Resetting Trigger" which means that the trigger resets much like a standard pistol, and continued presses of the trigger will result in more laser strikes, whereas the LaserLyte solution requires manually operating the slide to reset the striker before a second shot.
I have put together powerpoints of targets I want to practice shooting, and using that as my training. I have a big deck of deer and elk that helps me identify and shoot the vitals quickly, or pass on shots that are not ethical to take. Even though I am a bow hunter, this has helped my hunting decision making immensely. I also have a powerpoint deck of hostile and friendly human targets to practice similar skills.
If the SIRT option isn't going to work for you, then you are best off getting an Airsoft gun that is a replica of your real gun, and practicing in an area that the plastic pellets won't harm anything.
If you have great eye alignment and focus, and competent gun manipulations like drawing, reholstering, reloading, etc., then at the range you can work on recoil management and be much more focused. I go out and shoot a box of live rounds every once in a while, but I have found that most of my skill increases come in my house with laser trainer.