In Jamaica it's better don't go round by yourselves. The drive is on the left and it could be a problem, besides many drivers are just a little crazy!!
We were a group of 10 Italian tourist, so we could take a minibus. The driver was a nice guy and he has been our guide all through the week. Indeed he took us to Runaway Bay beach every day as well as to be a good tourist guide on our trips.
If you'll spend your holiday at Runaway Bay or at Salem and want to go round, you can trust him. His name is Carlton and if you want to contact him I have his address.