Anyone can participate if they meet a few requirements first. Participants must have a valid reddit account to sign up with Reddit Gifts. You must create a redditgifts.com account, verify your email address, and successfully link an existing reddit account. Once you have completed these steps, our system will be able to match you in whatever upcoming exchanges you sign up for.
Please note that multiple accounts are not allowed and you can only sign up once per exchange. The number of different exchanges you can participate in at one time is based on the number of credits you have earned. Everyone starts with 1 credit.
Matching happens at different times of the sign up close date for each exchange. This generally happens between 8 a.m. and noon Pacific so be sure to sign up and link your account and validate your email address before the close of sign ups. Email verification can be slow when the system is busy so please don't wait until the last minute to sign up. This could cause you to not qualify for matching.
Please see this blog post for more tips and information. It is Secret Santa centric but most information, other than matching dates, applies to all exchanges.