Note that in summer Rome is very hot indeed, and if you are walking around the city, which is a must, arm yourself with an adequate water supply before you set out. Be advised that when your bottle runs out, it is safe to drink the water that is on hand practically on every street corner. This includes archeological sites such as the Palatine Hill, the water spouts there are at the North end, near the Forum.

Now here comes the rip-off warning: you should normally pay under and certainly never more than 1 euro for a small bottle of water.  Buy at a locals' bar or supermarket and refill your bottle from a street fountain. Certainly do not pay the 4 euros to the mobile van vendors, asking for a small bottle of coke or ice tea.

Many bars will charge roughly double the price for sitting down and having a soft drink as off the tourist track will. It is however common in Italy to pay more for sitting and getting service. But sometimes they do go over the line. Specially be aware of coffee shop on your right when going downhill from Capitoline Museums to Santa Maria in Cosmedin church (where the Mouth of Truth is located). There espresso is 1,5e for standing and 5e when sitting! Above all, it is nothing to write home about, the boss is angry and does not speak a word of English. So check the prices before you sit.  It is still better to takeaway and sit by a fountain.

Always make sure that the cab you get in has a meter and it is licenced, 

Never never leave your wallet/card on a table when paying for a meal like you would in blighty, make sure your wallet is in your hand or in the front pocket of jeans....thanks to the kindly proprietor who pointed this out