Online web design business: Contract or not?

I am doing a web design and development business planning. The system is client buy a website package online >> make a payment >> I collect their requirement >> We work together until the end of the project (no face-to-face meeting, everything has done online). But when it comes to the contract which specify deeply the details of the job, including terms and conditions, I am quite not sure where to put these. How do you people do, either you:

1. Create a contract in PDF format, you sign and then you let client signs, you both exchange the PDF file online (digitally signed)? << This event has to occur BEFORE they make a payment?
   OR
2. You create a contract, terms & conditions page on your website before proceeding them to the payment process, make sure client ticks/agrees over the online format, after client agrees, then you proceed them to the payment page. Is that's how it's done?
   • What is the best approach in doing this process?
   • Is it the ticking over the checkbox means the clients sign/agree with the terms and conditions and could used as a legally binding between both parties?
   • What you should include within the box in order to clarify and reassure client before they proceed to the payment process: full contract, terms and conditions, else?

Both will work. Just some quick background, for a contract to be valid, all parties must assent to the terms.

The emailing a pdf approach: This would make it much easier to prove assent. The user actually signed and sent the contract. That said, it is more work for your users.

The check-box approach: These are usually enforceable as long as the user actually assented to the terms. These could possibly be enforceable with as little as a link to the TOS before the checkbox. But, I would put a scrollable text area with the entire contract in it. See this article for a court that disregarded a check-box agreement for not being clear enough to prove assent: http://blog.ericgoldman.org/archives/2011/10/court_disregard.htm The only non-legal comment I would have about the check-box agreement, is that they usually have the same contact for all-users (Facebook's TOS for example). It seems like you want a different contract for each user and this might add to the complexity of your web application.