This is how I did it:
The rule of thumb is 3 parts water to 2 of glycerine, so I used 75ml water and 25ml glycerine. Just mix them in the bottle and add some essential oils if wished. I used lavender and tea tree for the calming benefits which make it ideal for oily or combination skin. Shake it together. You're done!
Glycerine is also a natural moisturiser so will keep your skin hydrated while not clogging your pores. A double win!
Let me know in the comments below how you got on with it.