No grace period means that finance charges accrue from the time a transaction is posted to your account. Some issuers will accrue finance charges from the 'transaction date', which is the actual date the transaction took place. The posting date may be later due to the method the merchant uses to process the charge. In addition, paying the 'new balance' shown on your statement will not fully pay off the account as there will be residual finance charges from the date your statement was closed until the day they receive your check, so if you want to zero out your balance you have to guestimate the residual finance charge and overpay. It's all a pain in the neck and a big guessing game. Try and get a card with a grace period. You will be much less aggravated.
It's also a good idea to guesstimate how much you'll use the card and for what. Many cards offer the option of a lower APR for a reduced or for no grace period. You'll have to do the math to find the better deal. It's a different story if you're asking about Cross Country or Providian. They offer no grace period simply to gouge you for as much money as they can.
