From: Seoul, Korea
I have tried the coral sea scenario and intend to go back to it again. I had seen someone suggest ai vs ai until mid-42 then jump in and take control of the allies. I thought I'd try that.
I suggested that (and I think I got the idea from Bullwinkle). However, what I do is run the game in Continuous mode while I do something else (e.g. sleep, read, surf the internet, etc.) and then a couple of hours later stop it and see if the game is at a good point to insert myself. If not, I run it some more on Continuous and repeat. I wouldn't actually watch what the computer does as I don't think much could be learned. Also, if the Allied side doesn't send out the CVs and BBs, that's probably good as Shellshock says.
If you are just starting out, a scenario like Coral Sea would be good to play to learn the mechanics, like Gen Patton says. My method is good once you have a pretty good idea of what's going on.
Beer, because barley makes lousy bread.