Ideas for dues/information

[heyitsjennay]

I am currently treasurer of my sorority and our finance system is below par. I have looked into online services and actually began to use it for the chapter, which so far has been going great. My question is how do you all set up when dues are due? We currently do not have a system and most people rack up a lot of money owed and pay it off at the end of the semester which makes it very hard to collect any "spending" money.
Also, girls order t-shirts and miscellaneous items and wait to pay for that as well is there any way to enforce paying for those items within a certain time period?

Thanks!