Need to order choices.. in options_for_select

I pretty new to Ruby and RoR.

I know that options_for_select takes a Hash.

<select name="credit_card_type">
<%= options_for_select({ "" => "", "Visa" => "VISA", "Mastercard" =>
"MC", "American Express" => "AMEX", "Discover" => "DSC" }, "") %>

So what is the best way to do this then? I want it to be ordered...
And if options_for_select is wrong, what is right?

And as a side question, I expected to find a Plugin for CreditCard
entry, but I haven't found it. Anybody know of one?

Thanks for any suggestions,