It can be hard to get your camera to focus on the main element of your shot if the object is tiny in comparison with the background. Manual focus is a way of getting round this problem, but point-and-shoot digital cameras rarely have a manual focus feature. So you'll need a little practice.
Focus the camera on something more substantial nearby - a leaf, for instance - and half depress the shutter button. Move your camera back in line with your subject and, still with the shutter half-depressed, slowly move towards the subject. Once the subject is focused on your screen, take the picture.
A tripod can be virtually impossible to use in macro mode because of the closeness of the lens. It will help the sharpness of your shot if you half-press the shutter button, wait for your shot to focus, then shoot. This will minimise shake. At such close range the slightest movement will ruin your shot.
If you're still getting blurry shots, you can significantly reduce camera shake by using the self-timer. This feature will help you avoid the hand movement that inevitably happens when you press the button to take a shot and it will allow you to brace the camera properly with both hands.