Congrats! Get your girlfriend hooked and you might be set for life. Worked for me.
The best advice I can give you is to seek out someone else to give your GF instruction. The "couples dynamic" often comes into play when one spouse/SO tries to teach the other. It's often better to get instruction from someone outside the relationship.
That being said, if you can't find anyone and need to instruct her yourself, here are some suggestions. (These are handgun focused because that's what I'm most familiar with teaching)
1. Keep it safe. Teach her the four rules and make sure she understands them and knows why they are important. Make sure you both wear eye and ear protection. Have her double up and plugs and muffs. Really. It helps reduce the blast and noise and makes it easier to learn.
2. Keep it fun. If learning to shoot or going to range become a chore, she won't want to do it. Reactive targets are good for this. Even if your range restricts you to paper targets only, the "Shoot 'N See" targets work well to give newbies instant feedback. You can also blow up ballons and staple them by the tied off end the backstop. If possible, shoot at short range at first. Start as close as 10 or 15 feet and move back when she's comfortable and getting good hits. This keeps the frustration level down.
3. Have her focus on the basics:
1. Stance - Isoceles or modified Iso is the easiest to learn. Have her stand facing the target with her legs shoulder length apart (more or less). When she finds a comfortable position, have her bend her knees slightly and lean forward into the gun just a bit. She wants to avoid the backward, "leaning away from the gun" stance that is common with new female shooters. To avoid this, have her pivot forward at the waist slightly. One trick is tell her to stick her but out just a little bit to bring her torso forward. Her arms should be straight, fully extended, but not locked.
Have her try that traditional isoceles stance first. Than have her try placing her strong side leg back a little into more of a modified isoceles stance. Some people have better balance one way, other's find the modified works better. Her arms should still be straight and not-quite locked.
2. Grip - Show her how to properly grip the handgun in the web of her hand. Show her how the support hand wraps around the dominant hand. Keep both thumbs on the same side of the pistol to avoid slide bite.
3. Finger placement - Her finger should be placed on the trigger somewhere between the pad and the first joint. The pad gives the most precise control, but doesn't always work if the gun is large for her hand or if the trigger is heavy. She should find the spot that works the best for her and for that particular gun.
4. Trigger pull - Have her work on a SMOOTH pull. She needs to practice pulling the trigger straight back without disturbing the gun. If she develops a good, smooth trigger pull now, she'll be light years ahead later. Do a little dry fire at the range at the start of each session. Even five minutes or less helps.
5. Sight alignment - I put this AFTER trigger pull deliberately. She needs to know and understand the importance of correct sight alignment, BUT she needs to understand that a good trigger pull is more important then having a perfect sight picture when the shot breaks. Even if the sights are off slightly, if the trigger is pulled smoothly, the shot will be on the target. On the other hand, even if the sights are aligned perfectly, if the trigger is jerked because the shooter tried to break that "perfect" shot, the bullet will go into the dirt.
Btw, it helps to literally draw a little sight picture on the back of a target or a scrap of paper to show her what correct sight alignment looks like. Draw a pic with the front sight out of the notch too high as well so she can compare the two.
In my opinion, after safety, the most important thing for a new shooter to learn is good trigger control. The sights can be off, and the stance can be less than perfect, but if the trigger control is good, the rest will fall into place.
Btw, go to the NRA.org website and find the "Basic Pistol" book. It's about $6 and is well worth the money. You'll want to find the page on the website that lists the book for the general public. There's another page that has it listed as part of the student pack for the Basic Pistol class, but you can't buy the pack unless you are an instructor.
One last tip: Have her shoot a .22 almost exclusively at first. It's much easier to learn with the lower recoil and blast of a .22
This should be enough to get you started. Hope it helps.
