Use a tuner to check the pitches while you are tuning. Turn on the tuner and set it by your cello on a nearby chair where you can easily see how much the strings are flat or sharp. Flat strings will need to be tightened to raise the pitch; sharp strings need to be loosened to lower the pitch. The tuner will indicate the level of sharpness or flatness either with a needle or a digital read-out.
Tune the strings from lowest to highest. Start with the C string. Press in on the tuning peg lightly as you turn to increase the tension in the string. Tension will hold the string in place, so you don't need to push the peg in too much.
Adjust the remaining strings to within one to two notes of the appropriate pitch for each string. The remaining strings should be tuned to G, D and A. A is the highest string and the most delicate, so you must tune this string last.
Use the fine-tuners located at the bass of each string to fine-tune the cello to the final pitch. The fine-tuners are small, round knobs that can be turned to adjust the pitch much more accurately than the tuning pegs. However, they can adjust the pitch by only about one note.