i generally use two sizes of syringe for my mixes, a 2ml syringe and a 5ml one, these are fine for up to 30ml, the 2ml syringe is graduated in 10ths of a ml so very accurate quantities can be obtained
the bonus with using a calculator and syringes is you know exactly what level of nicotine you're consuming and makes it easier to reduce the level accurately plus you can also experiment with the flavour concentrate/vg/pg ratio for better tastes/throat hit for yourself and be able to note the measurements down so that again you can replicate or alter to suit yourself
don't throw away any empty ejuice bottles as they can be washed and reused, dripper nipples can be pulled out of all the bottles for refilling and then put back, even the 10ml bottles can be useful for a little day out pocket sized backup supply