Used to own a business that sold advertising in the same college market.
Be very careful when extending credit to advertisers. The sale is only one part. The other part is collecting the money. Would suggest you try and not extend credit and get paid if at all possible by credit card. The back office and aggravation can be quite aggravating. People will take advantage of you. They will tell you to show up to get a check (after you pester them) and then they won't have the check and tell you to return.
Edit: I made this comment because the op had mentioned closing sales in person (or perhaps over the phone). This is not the same as a website with a "pay here" link. When you close in person there will always be customers who attempt to get credit terms. Think in particular what a chain restaurant would do or a company where the management is located elsewhere. They will say "send us a bill and yeah sure we will pay" or "can I give you a PO". So the question is how lucky do you feel. Of course if the COGS is very low it pays to take a risk. But just get ready to have to follow up multiple times over many months to collect that money. And don't act like it's in the bank because it's not in the bank.
Be very careful when extending credit to advertisers. The sale is only one part. The other part is collecting the money. Would suggest you try and not extend credit and get paid if at all possible by credit card. The back office and aggravation can be quite aggravating. People will take advantage of you. They will tell you to show up to get a check (after you pester them) and then they won't have the check and tell you to return.
Edit: I made this comment because the op had mentioned closing sales in person (or perhaps over the phone). This is not the same as a website with a "pay here" link. When you close in person there will always be customers who attempt to get credit terms. Think in particular what a chain restaurant would do or a company where the management is located elsewhere. They will say "send us a bill and yeah sure we will pay" or "can I give you a PO". So the question is how lucky do you feel. Of course if the COGS is very low it pays to take a risk. But just get ready to have to follow up multiple times over many months to collect that money. And don't act like it's in the bank because it's not in the bank.