As someone who learned the very hard way MAKE SURE YOU PICKED THE RIGHT COMPANY FOR YOUR CC SERVICES!!!!!!
Shop around hard, at least talk to other companies as to who they use and how they like them. They are all peaches and cream getting you to sign up but turn into a real pain in the a$$ should you want something after the paprework is signed.
Especially the term of agreements. Funny thing is you have to sign agreements with multiple entities and the magic timeline doesn't match. SOOOO you end one term and are married to somebody else after the fact.
PLEASE do your homework.
quick note about this, and to expand since I wrote my initial response quickly.
We do not accept returns. This is stated clearly on all order and quote forms as part of our general disclaimer. We do re-run orders free of charge if we mess up, and we drop everything and do it immediately. Be sure to cover yourself on your forms if you choose to take a stance like this- some clients may be a pain about it, but explain it in relation to their business. Find a product they can only sell to one client and could never resell once returned- a custom item. They'll understand quickly.
With credit cards, you can get bitten with chargebacks, it's good to have a letter prepared to fire back with the variables of the incident as quickly as possible. Every moment that passes decreases the chances for a favourable outcome for you. For contracts, find a no-contract CC processor if this is the route you're taking- we use payquake (payquake.com). No setup/monthly maintenance, 9$/mo minimum and no contract.