Hi,
Sorry no words of wisdom or even a guarantee what I suggest'll be effective. A few thoughts follow in any case.
Basically people want some bang for their buck, they want to know
what they'll be paying for and what they'll get in return for paying money. Obviously what they'll get is the opportunity to participate in activities which wouldn't be possible unless the group had funds as even posters cost $$.
If possible have either a calendar of events or a clear idea on the sort of events and activities you plan to offer. And be ready to answer the question of "what will our dues go on" - a budget you create will tell you this (maybe refreshmts, tshirts, subsidising events, supplies etc things you already know). There is a direct relationship between how much you can do and having funds to facilitate doing stuff.
You
can offer things like incentives (less dues) for paying earlier or in one go, but that might not be the best option if they're people uncomfortable about the dues, period. Yes, if you don't pay you don't play and without dues the group can't really do anything you just need a realistic sum so you can do stuff but not scare everyone away and then need to get that message across of all the benefits.