I've a 40 x 16 system which gives you an even number of teeth in both. If you keep these in phase after you remove the wheel and put it back, it apparently gives a wear advantage. If not, and you haven't changed the wheel for a long time, it's noisy.
I've marked the chainwheel by making a small mark on the chainguard, which I have, corresponding to a tooth with a narrow link.
I used to clean one tooth on the back and use this as a guide, but this was a bit finicky and I've thought of a better way.
Mark the circle under the relevant tooth by wedging something into it. In this case a small circle of plastic from some kind of electrical plastic thing I found lying around. Anything that would last would do.
See picture.