All billing for permanent clients  goes through PayPal.  Here is my address:  Please don’t request for any other places-I’ve had bad experiences. 
Billing is done one of two times: For shorter projects (ie. 10 articles or less) I bill when the project is completed.  For long projects, (such as 20+ articles) I bill on Wednesday, but only if I’ve done at least 10 articles.  If you do not received 10 articles from me for that week, don’t expect a bill.  This is done because it’s easier to manage the bookkeeping for huge projects when it’s done in chunks.  Please pay your bill by Sunday as I pull out Sunday so I can be paid for Monday.  (my bank policy, it’s very strange!)  I will send an invoice via Paypal detailing how much you owe me-I’ve been told this makes payment easier.  All payments are done in USD-I shop online, so this is easiest.  For anything other than articles, such as editing or e-books, I bill when the project is done.
Please note: if I bill you for a completed project, I will not work on anything further for you until the bill is paid.  This isn’t because I mistrust you, but rather because it’s easier for bookkeeping.
Prices are negotiable, but don’t insult me by offering a low price.  I’m sorry to say that I am motivated a tiny bit by simple greed-if you pay more, I’m more likely to give you slightly preferential treatment.  On this note though, I am also motivated by respectfullness and friendliness, so keep that in mind.  I also like bonuses.  Bonuses gets you an excited thank you note. 

Thank you!