Bob,
Aperture priority is my favourite mode as well, gives me the most control without really doing anything manually. But you have to keep an eye on the other settings as well. You don't want to have to slow shutter speed when hand held, you don't want to drive the iso into the limit.
But you can use the programs to determine what you want as well. They are good as well, especially hand held.
Some generic DSLR tips:
Rather than (only) reading a manual, there is usually a good book available with practice tips, showing you what the settings do rather than giving them to you in technical terms. Usually cost around £10 on amazon.
I also downloaded a couple of iPhone apps for my DSLR. Quick user reference guides and always available. And search able.
There is nothing you can't learn on youtube. There are a lot of rubbish tutorials out there, but once you find a poster you like the teaching style of, there will be a huge back catalogue on anything your camera can do.
There will be tutorials specific to your camera, and there will be generic ones teaching photography. I prefer the 2nd ones.
Podcasts as well.
Test at home. I booked a safari, I will go to Richmond Park and try shooting some deer there to test settings. If the deer isn't there,I find a path full of dog walkers. Do you plan landscapes, monuments, ... , find something similar to test. Try different light situations.
That way you can try every setting and know what they do in that kind of situation.
On location take lots of shots. I took about 60 shots of the Capitol in Washington, liked about 4 of them, but 2 were real winners. If you only take 2 shots you might not get any winner. I took 30 of the white house, nothing I liked. It happens.
I will also take a snap and shot camera with me. Any camera can fail, and it only cost about £60 to have at least something. Make them take matching memory cards.
