Even though measuring by volume is not a totally accurate measure it will probably suffice in the very beginning. It's recommended to dilute the EOs before blending to 10-20% in carrier oil or alcohol. You can use a disposable pipette to measure out 1-2mls of EO then add enough carrier oil or alcohol to make it up to 10 mls in total. Giving you a dilution 10-20%.
The rest is quite simple.
20% of 60 drops is 12 drops
50% of 60 drops is 30 drops etc...
Your final blend will then already be diluted to 10-20%. if you found it too strong you could add 60 drops of your carrier and then have a 5-10% dilution.