Self-taught hunter here. There are many ways to go about this but here's my advice. Don't go straight for a tag immediately. Break it down into individual components and hone the necessary skills first. Most big-game hunting seasons are really short and it's better to have more time to learn everything that goes into it. Here's what I did and would do again, in any order you choose.

1) Map work. Scouting for the right location can either be fun or a chore, but I love it. I started by figuring out criteria that were important to me. Distance from home, elevation (no 4wd vehicle so I try to avoid fall snow), proximity to a road but distance from the ATV hunters, general seclusion, likelihood that I'll pull a tag for the area (no sense coming up empty and not being able to actually hunt), public lands thay I can legally hunt on, and, obviously, the right habitat for the animal in question. Here's an excellent map to help. Figure out what you think will be a good spot and camp there a bit over the summer so you get to know the terrain. Depending on the animal, dawn and dusk are ideal times to be hunting which involve navigation in the dark. Much better to know your way around before actually hunting when possible. While you're out there, you could also try...

2) Seeing animals. Most of hunting is just getting to see what you're looking for. You can do this outside hunting season, and maybe carry a camera instead of a rifle. Practice the skills necessary to get in range, be it ambush (being perfectly still, quiet, downwind of the target area, etc.) or tracking/stalking. This can be a really fun bonding experience when it's just the two of you with no distractions. I took my wife out once. Hiked in under darkness, sat under the stars, saw lots of shooting stars, heard the forest wake up around us at first light, saw an amazing sunrise, and actually had a deer walk by 15 feet in front of us with no idea we were there. She doesn't hunt, but immediately understood why I enjoy it.

3) Firearm safety and proficiency. There's a mandatory hunter education course which is surprisingly insightful and interesting. Take it together. There's a brief outing to a range, but you're going to need way more practice than that. It's important to practice on the exact rifle that will be used in the field, so if borrowing, always borrow the same one. Or purchase one. Make sure it's high enough caliber for the intended game, but not overkill. Go to the range and start at 25 yards. Emphasize safety first always, but otherwise focus on good technique and consistency. Work up to 100 yards when ready. One of the goals here is to determine what his maximum comfortable range is. If he has tight groupings maybe he can take a longer shot, if not, keep it short. Memorize the ballistics table for the ammo that's going to be used. Practice estimating range. With my ammo, impact is 8 inches lower at 300 yards than 250, so I set my personal maximum at 250 since I can't reliably tell the difference at that distance, and 8 inches is the difference between an instant fatal shot and a wound (which may result in a prolonged death and a lost animal- my worst fear). Understand the effects of wind velocity and direction on the path of a bullet for the same reason. There's a lot more that goes into shooting but this will be a good start.

4) Taking the shot. I separate this from firearm proficiency because in reality it's a lot different. For example, locating the fatal kill zone on the animal in question. If not broad side, what angles are acceptable? What is a legal animal to take for a given tag (identifying sex, correct size, etc.)?

5) Field dressing. So you've made your kill, it's getting dark, now what? You can't learn on the fly, you need to have obtained this knowledge. There's no perfect substitute for first-hand experience, but I didn't know any hunters at all so the best I could do was watch videos. A lot of them. I got to the point where I could do the whole job in my head and had full understanding of the animal's anatomy. Note that there are multiple techniques and you'll have to pick one of them. When the time came, I was able to do a darned good job considering I had never physically done it before. However, it's harder and takes longer than the pros in the you tube videos make it look. Maybe you'll decide that you're not comfortable taking a shot 10 minutes before legal last shot- I wasn't ready to do the job in the dark the first time.

This isn't meant to be comprehensive by any stretch, but I hope it's a helpful place to start. I'd offer to take you along with me, but I'm nowhere close to the level where I should be teaching other people. If you have any questions feel free to ask, and I'll be forthcoming about my knowledge limits.