Metronomes are a musician's best friend! When used appropriately, they will help you be consistent in your tempo, accuracy, and pacing of your own progress. SoundCorset is a great free metronome app for smartphones and tablets. It also has a tuning function as well.
One of the neat functions of SoundCorset is the ability to subdivide big beats if you are counting in eigth notes, triplets (or 6/8), or another denomination. Here is a quick walkthrough on how to use this feature...
When you open the app go to the metronome section, you' see this your basics: a slider to select the tempo and one to select the volume...etc, etc...Just below the slider that controls tempo, there various buttons for dividing measures and beats.
The drop down option to the far left allows you to emphasize the first beat of each measure and indicate how many beats are in a measure.
The 2nd button to the left shows a pair of 8th notes. Selecting this option will divide each beat in TWO (2) so you can hear quarter notes on the "big beats" and 8th notes on the off beats.
The 3rd button has an icon of triplets, or three 8th notes grouped together. Selecting this option will allow you to subdivide those "big beats" by three. This is useful in early Suzuki songs like O Come Little Children (Volume 1) and May Time (Volume 2.)
Using this button is very helpful when first learning a piece with a 6/8 time signature. It reinforces the somewhat lilting feeling of grouping three small beats into one big beat: ONE-two-three, FOUR-five-six... and so on.
Selecting the icon with 3 dots on the far right will give you even more options if you more complicated rhythms. You can divide a quarter into four 16th notes (perhaps for Scherzo in Volume 3.) And there are other options for dotted rhythms too.
If you are feeling adventurous, or if you have something that is rhythmically EXTREMELY complicated, you can select "create new" and customize what your metronome plays. I have only used this feature once for some gnarly orchestra music so I don't have any suggestions for students applying it to standard cello literature at the moment. However, that shouldn't stop you from experimenting!