Here's what I'd recommend trying, for both scenarios.
If you have an empty plastic milk jug at home or empty clear film roll container, those are good light diffusers as well... just cut a film canister enough so it can slip over your flash or cut a decent size portion of the milk jug into a square and hold it in front of the flash and see how that works for you. If you want something more professional looking, Gary Fong has something called 'The Puffer', I have one and it's great in a pinch - just depends on what kind of camera you have if one will work or not.
Some other tips:
lichtmeister: How to improve your built-in flash
Flash isn't a bad thing, but you have to use it properly. If you can't or don't want to use flash, taking a photo next to a window with white thing curtains works great as well, it's a huge diffuser!
When all else fails, some cheesecloth over a standard lap will work wonders as well (just don't let it get hot).
But, what I really like using are various poster boards (I like white and black myself). You can quickly assemble a 3 sided 'box' (bottom, back, 2 sides), white bounces light in a great way and if you have 3 sides that are white you'll get some instant gratification as long as you have some control over the light output.
Sometimes what happens in 'Auto' mode is that the camera will adjust the exposure for any black parts of the subject, which will of course blow out some of the shiny parts, especially if you use direct flash (direct flash will also give 'hot spots').
Some other things to consider:
Distance to subject
Distance from subject to background
Distance of light source