What camera?

Focus peaking, a focus screen, punch in on focus, all of these things can make it dramatically easier.

But you still need to practice. After a while it becomes muscle memory to hit distances an you refine by eye. Zone focusing is also a thing.

Don’t shoot action wide open unless you have a high tolerance for misses; there’s a reason the old press photographer adage was “f/8 and be there”.

As others have said, your difficulty might be from shootingnwith a shallow depth of field. Instead of shooting atblike f/1.4, f/1.8, or whatever you widest apwrture is… shoot at like f/8. This increases your depth of field, makes it easier to get what you want in the focal plane while manually focusing. Save wide open aperture for controlled environments/subjects when manual focusing.

The above and practice isnoretty much how you get better. The above at least eliminates a potential technical difficulty you might be experiencing.

Also, make sure your camera’s diopter is tuned to your shooting eye. It’s way easier to tell if you’re sharply focussed

Practice.

But nobody in this sub is looking over your shoulder: you gotta provide more information to narrow down the responses. Does your camera even have the focus peaking others mention?

What camera model and what lens as precisely as you know it? A fully manual rangefinder or SLR is going to have different stuff than a modern DSLR or mirrorless. Is it able to take sharp photos in static and controlled settings, like a focus test chart?

And if you have something modern with autofocus available, what about it makes you not want to use it?

It is mostly practice

However, the camera and lens features may made your manual focusing journey easier or difficult. First, modern lenses and cameras are not made for manual focusing. There is no scale. Fly by wire is not precise because it scales based on how fast you focus. They tend to have a shorter focus throw. Older cameras can have a focusing system optimized far manual focusing like the split prism focusing screen.

Keep doing it, or take it off 1.8/1.2 whatever the widest aperture is and shoot at 2.8 or 4. This will give you a deeper DOF, making it easier to find focus quickly.

Try an older / adapted lens that has focus distances on it and practice range focusing.

If your camera has focus peaking, enable that.

I have focus zoom set to a custom button too so I can zoom in and check focus, but that’s mostly for longer setups, something as quick as street it might not be as useful.

Practice. Practice with video or live view is best. If you can track someone/something in focus for seconds-minutes, you can probably grab it quickly for a single shot.

Use the distance markings on the barrel. Carry a tape measure and play the distance game when you’re not shooting(How far am I to this window, window to sink, etc. etc.).

You can also set focus to a certain distance for a frame you may want, and when walking about take your shots at that distance…used this method for street photography with a very troublesome old film camera.

Use a Depth of Field Calculator and understand the throw of your lens + depth with chosen aperture and sensor size. Typically, your throw is longer the closer to the sensor and much shorter for distances further away(1’-4’ might be quite a difficult focus movement if you’re framing up quickly on the street…10’-30’ is likely pretty small and fast).

Focus magnification is your best friend on a digital camera, ideally on a button you can easily press while looking at viewfinder/monitor. Peaking/focus magnification isn’t very reliable(false positives, etc.). Shooting in a view/monitor that displays black and white also anecdotally helps(the contrast increases ability to perceived sharpness, which color can distract from and make sharp edges less neat. I personally find it helpful).

I find photographing pets to be good practice. They move quickly, quicker than most humans. If you can manual focus a playful puppy, you are ready to hit the streets.

For street, you need to zone focus. Stop it down and see how that works.

Practice and use focus peaking if your camera has it. Also, depth of field can be your friend.

Older cameras and lenses were designed for manual focus. Both in the view finders and in the giant lens focus rings with big rubber grips. Cameras were meant to be used manually before AF came along. It is an unfortunate fact of modern cameras that they are optimized and designed to be used as automatically as possible and only begrudgingly allow manual use anymore. People were good at the lost art of focusing in the manual SLR days because the cameras made it easy and people had plenty of practice at it.

The other problem in play is the modern philosophy of photography where sharpness of focus is seemingly even more important than composition. This is an expected artifact of the availability of finely focusing cameras among people who can’t really take a picture. So here we are.

One thing I like is starting the lens at infinity, or further away than I know the subject is, bringing it up to my eye while starting to rotate the lens to bring the focus closer, so you always know the subject is going to come into focus from further away. This way you don’t have to hunt back and forth, just stop turning it closer when it’s in focus and shoot.

Do in it more often than you have been.

I would just try auto focusing instead. The stigma against auto focus is silly if that’s why you are using manual focus. If it’s the cheap 1.8 canon 50mm then I know how short of a distance that lens has to focus. Will be near impossible to get solid stuff in-focus that quickly and you’ll just lose good photos.