For Mills style start with a 8step sequence, then experiment with different pitches of the OSCs, different waves etc. With the audio mod you can get excellent Mills style Bell sounds. There is much interaction between the parameters, so a millimeter knob twist might take you to another universe...
Also, "groove" is mostly about proper tempo settings (ENVs, FX times, LFOs)
Especially on the ENVs there is a lot to learn. Just one example: what a difference a shorter filter release makes combined with a longer amp release. Just one example...
I'm sure you will find all out - enjoy the ride:)