I'm not sure exactly what you are asking. As JMLBrats said, there are rental agencies that some people use.
If you are looking to rent points here, through the rent/trade board, then a few points would be to:
1) Look at number of posts - not to say that a new poster is unreliable...just that those with higher post counts have some history behind them.
2) Never send payment by Western Union or other money order.
3) Be sure to have verifiable contact info of the owner, email addresses, phone numbers, home address, etc.
4) Be sure you have an agreement or contract that spells out the specifics of your rental...payment dates, cancellation policy (if any), deposit forfeiture, etc.