Q：What is the fastest way to develop a topspin stroke without a tennis coach?

A：Practice. Ideally, a daily hitting partner would be best - it's important to be able to strike a variety of balls in or out of your hitting zone or also on the run. If this isn't possible, a ball machine is much better than no practice at all. Start with the basics and work your way up to more advanced techniques. It will take you a few years of heavy practice until you develop what I would consider to be a solid top spin forehand/backhand. Let's look at the forehand. This is going to be a long answer (I love talking about forehands - it was my strongest shot when I used to play competitively, and I got pretty good at putting a lot of pace behind em):
For God's sake, don't try to hit every ball as hard as you can while you're developing your stroke. I know it looks cool, but it's only developing bad habits.
When you start out, focus exclusively on swinging low to high, brushing up the back of the ball. This is the most primitive way of generating top spin and sacrifices a lot of pace, but it's the way to start.
Hopefully you're using a semi-western or western grip. They're the easiest to start with, and using an Eastern grip to me feels flat out awkward. Focus on keeping your wrist laid back and locked through your swing. Don't try anything fancy with your wrist. Keep your "takeback" simple - no elaborate form. Make sure you drop your racquet head at the end of your takeback/the start of your swing.
Hit at least 7-8 thousand forehands (I just picked this number randomly, but the point is that you should be practicing a lot) until you feel comfortable with your technique in rallies. Be able to comfortably hit 20-30 forehands "in" consecutively while also applying a decent amount of pace.
Ideally you can also move balls around - don't just hit down the middle of the court all day. Emphasize bending your knees through the shot, stepping into it, and developing a smooth stroke that combines shoulder rotation fluidly with hip rotation. Try to hit the ball ~3-4 feet over the net with an average amount of pace. Try to get your balls to land between the service line and the baseline.
Here's a simple tip: when you start your forehand motion, point your left arm straight out to the fence your body faces, as seen below:

This forces your shoulders to line up with the ball, maximizing your shoulder rotation. Federer does this on literally every forehand he hits. Just one more reason why it was the best shot in the world a few years ago. Try to contact the ball as far out in front of you as you comfortably can.

Nothing good ever came out of contacting the ball late.
Once you feel like you have a good handle on a basic top spin forehand, it's time to learn the "windshield wiper" technique. This is the advanced way of generating top spin off the forehand side. It's used by good junior players, D1 college tennis players, and pro's alike (with varying effectiveness).
Swinging low to high is a cheap way of generating top spin, but you're losing a lot of power since you're not driving through the ball with a flatter swing style. On the other hand, if you swing directly through the ball without putting any spin on it at all, you're going to have a bad time with errant balls flying all over the place.
Using your wrist to generate your top spin instead of your entire swing allows you to flatten your stroke to put more power directly behind your balls while still maintaining a decent shot percentage (as you'll figure out, top spin helps your balls fall into the court).
So what is the windshield wiper motion? Extend your arm straight out. Now without moving your arm, pretend you're happily waving at someone. See how your wrist is rotating? That's the basis of the motion. The racquet head mirrors this motion in your swing, and in doing so, it brushes up the back of the ball to generate top spin. It sounds simple, but it takes a lot of practice and careful body control to develop a solid top spin stroke with this technique.
First, watch a lot of slow motion videos of the forehands of Federer, Verdasco, Nadal, etc. Pause them repeatedly. Step through them second by second. It's important to recognize what a good "wiper" motion looks like. I spent about 4 years of my junior career obsessed with Federer's forehand back in ~2005, and to be honest, it definitely helped me improve mine. Please ignore the poor cropping.
First note Fernando Verdasco's wrist. It's completely laid back. This is key. Keeping it laid back allows you to maximize the "rotational range" of the wrist and, henceforce, the racquet head.

The only way to master to this is through a lot of practice. Easily thousands of balls.
Don't be impatient with this. It takes a few years to master this technique and will feel very awkward when you start out. Eventually, muscle memory will take over and the wrist rotation will feel second nature in your swing. Hopefully this gives you a better idea of the technique. A coach helps to point out what you're doing wrong, but there really isn't any magic to putting top spin on the ball.
On the other hand, putting extreme amounts of pace (upwards of 85-90 mph) on the ball is much more difficult ;)

好能说 不过 说得好

学渣哭了

看了一下，大概说在没有教练的情况下（非土豪）如何提高正手.1:首先你要勤奋练习。2：你要有基友陪你练习。3：没基友的可以用发球机（在天朝发球机可比业余教练贵）。3：要多看职业选手慢动作，像小德，费神，纳豆等。4：想打出上旋可以让球拍从下往上运动，不过这可没有穿透力，要用手腕去产生上旋，配合雨刷式随挥。最后一定要勤于练习！

要火

幸好阅读能力不差。。。。