Depending on the pH meter used and the electrode used procedure can look slightly different, but in most cases pH measurements procedure will be at least very similar.

First of all - remember, that the electrode should be always immersed. Thus between pH measurements it should be put into a beaker with distilled water or - much better - KCl solution (0.1M to 1M). Don't worry that you will destroy the electrode moving it between solutions. It can easily survive minute in the air, but don't let it dry.

Second, equally important thing is - the electrode is very fragile. Bubble at the end is made of a very thin glass - the thinner the glass, the lower the internal electrode resistance, which is good for measurements. At the same time thin glass is very delicate, thus you should treat your electrode with care.

Ensure that pH meter is on. If you want high precision of measurements it is better to let the pH meter to warm up for some time (like 30 minutes) to ensure it will not drift later.

Before every single pH measurement, or before any series of uses, you must calibrate the pH electrode.

After calibration you are ready to measure the pH. Rinse the electrode and submerge it in the tested solution. Read the result and write it down in your lab notebook. Rinse the electrode and move it to the storage beaker. Done.

Please remember, that above outline is very general. Different pH meters may require slightly different operating procedures. You should consult your meter manual to be sure how to proceed and how to maintain the electrode.