Something that can help is to start the focus throw with the lens at Infinity, and move it rapidly and smoothly to the closer distances, and as soon as it looks good, STOP! Again, start at Infinity, rack inward, as soon as it looks good STOP! and you will be very,very close. A minor correction, or perhaps two, and you ought to be dead-on. This method works better than starting at close distance, and then trying to hit focus because of the rate of focus travel is rapid when coming inward, and much,much slower when going from near to far, and the human eye and brain are best at spotting "difference". When you focus from close to far, the difference is very subtle--when cranking from Infinity toward closer, it's easy to spot the "difference" where the lens goes from "out" to "in" focus.
Focusing can be improved by practicing, and the way I described to you is a very well-proven, old technique known by far fewer people than one might imagine. If you practice this, take a #2 pencil and literally make some kind of a mark to indicate the exact focus point it is that you "hit"...try three or four tries on a stationary target, and do this with targets at different distances. LITERALLY, practice focusing, and make pencil marks, to see how consistent you are at long, intermediate, and close ranges. Once you develop more of a feel for that camera/lens, you'll get better and better!
What you want to avoid is see-sawing back and forth, back and forth...when that happens, the eye and brain are "adapting" to an image that is pretty close.
A second tip: if the camera has a split-image focus aid, if you want to see if you are dead-on in focus, pick an edge, and move the camera up and down, and watch the edge: if the edge in the split-image rangefinder "shimmies", that edge is NOT in-focus!!! If the edge stays stationary, the focus is dead-on!