This trick will cause a red shell go around the entire track over and over until some unfortuanate opponent gets in the way, which causes a crash.
To do this, you must first be in first place. When you shoot a red shell along a long straight away, it will automatically get on an invisible track, which will cause it to go aound and around and arou... You get the idea. It's a good way to get the other karts who are in last place without moving from your current first place possission. Note that this trick doesn't work as well on some tracks as it may on others.
When planting a bannana or a fake item box, the best places to put them are within a bunch of item boxes or on sharp turns.
To guard against any unwanted shells or other karts, be sure to drag something behined you whenever possible by pressing and holding the "Z" button.
If you're stuck in the corner of a wall or something, use the Spin-Turn move explaned in the Kart Moves section.
Possibly one of the best tips that I can give you is to use Power Slides whenever and wherever possible. Try to et as many mini-turbos as you can.
Other good places to drop bannanas and fake item boxes are in narrow pathways that you occasionally come across, such as the entrance to the cave in Sherbet Land.
The entrances to shortcuts are also good places to drop them so that you wont
have any pesky followers. A good example would be on the jump to the cave shortut
in Koopa Troopa Beach. For more information on the courses, check out the Course Maps