Hi Folks
I am visiting the US in June.I plan to visit San Diego for a couple of days.I hope to rent a car and drive to the Grand Canyon then on to Yosemite and finally San Francisco.Any driving tips

Sounds like a fun trip.

That is significant driving. SD to GC has got to be 9 hours or so. GC to Yosemite is 15-18 hours.

Here is my eminently American advice:

Buy an inexpensive foam cooler in SD...try Walgreens or Walmart or Target and fill it with: ice, water, fruit, snacks. Get a map and look at it prior to getting behind the wheel. Stay in the right lane except to pass. Use your signals. Keep up with traffic. Right turns on red after stopping are legal and expected. Do not aggrivate the big trucks.

As placeu2 politely indicated, it's easy to underestimate distances when planning trips in the US, epecially in the West. As you plan your itinerary, check the distances and times in a software like Mapquest (hey, they might make small-scale mistakes, but they're fine for rough estimates). Consider the possibilities of intermediate stops at interesting placs, or in flying some of the longer intervals.

The driving time indicted above is about right. You can also check freetrip.com for milage, time and routing.

We did the San Diego-GC drive last October and stopped for lunch at the last rest stop in CA. It was the worst stop the entire trip from VA to CA to GC and back home. Dirty rest rooms, watery diluted hand soap, no towels, and no potable water. If you will be carrying a cooler as we did, try hold off for the first rest stop in AZ for lunch.

If you're coming from the UK...........
we drive on the other side.

...the "right" side!