Many pay sites offer you a chance to sample their offerings on a trial basis. For a low fee you (usually) gain full access to the site from two days to two weeks.
Be aware that, if you sign up for a trial you must cancel during a designated period or you will be rebilled for the monthly fee upon the expiration of the trial. Even more important, note that the designated period is sometimes one to three days less than the length of the trial, so you have to cancel before the trial's expiration in order to avoid the first monthly charge.
It's easy enough to avoid being caught by this little trick: the rebill clause in the Terms and Conditions agreement will clearly state when a rebill will be made. (Remember, when you cancel a trial you still have full access to the site until the end of the trial period.)
Terms and Conditions
Always scan the "Terms and Conditions" (T&C) agreement before signing up for a site. Of course you're not going to read the entire, legalistic, boring thing, but make sure to find the clauses regarding the rebill and cancellation terms, which are usually found around the middle of the agreement. If the terms are not clearly stated, do not join the site.
In the bad old days of the adult Internet, you really had to be wary of slippery language. Fortunately, in recent years misleading tactics around billing have become quite rare because both government regulators and credit card companies have cracked down on abusers.
Things To Look Out For
If you take a trial the monthly rebill may cost more than a regular monthly membership
When you take a trial you would expect that when it converts to a monthly membership the monthly price would be the regular 30-day price. For example, the regular monthly price for a site is $29.95; it offers a three day trial for $3.95. If you don't cancel the trial then you are billed $29.95 for the next month's access. That is usually the case, but with a few sites the $29.95 price only applies if you sign up for the monthly membership directly (rather than taking the trial.) For these sites, If you take the trial the monthly rebill could be as high as $39.95. So always check the rebill information which is either at the bottom of the join page or in the Terms and Conditions agreement so you aren't unpleasantly surprised.
Automatic trials to other sites
Sometimes on the join page there will be one or two check boxes that tell you that you'll get a "free trial" to some other site when you join the site you're actually interested in. We advise you to always indicate that you do not want this "bonus" offering. These bonus sites are usually crappy ones you would never want to be a member of and if you don't remember to cancel the trial for the bonus site you are going to get rebilled the monthly fee, which can be as high as $39.95.
Record the details
Keep a record of the details of your transaction, including: the date, username, password, subscription or transaction number (if any), and the credit card used. At the bottom of the sign-up page, you'll find the name that will appear on your credit card statement (it is rarely the actual website name).
You will always be asked for an email address when you sign up. Make sure you provide a legitimate email as you will receive a confirmation of your membership via email.