Don't confuse your pads. Each has a specific reason for being, and using them for more than one step can result in uneven gains or possibly damage the car.
Reserve extra pads and make sure you have enough polishing fluid. You never know when you might spill or damage something you need.
Store mats and tools in a clean place. You don't want to try to polish your car with a dirty pad.
If you're not sure about your polishing skills (it's okay if you are), it might be a good idea to pick up old doors or body panels from the junkyard to practice.
Start with a clean car. If you rub on dead bugs and dirt, your buff work won't look as good.
Don't polish in one spot for too long. Heat can damage paint.
You can hand polish in a pinch, but it will require some elbow grease.
Try working in the shade and allow yourself enough time to polish before the solution dries. Sunlight and direct heat can greatly speed up the process and can damage your paint again.
Some available polishing kits will provide orientation in stages - usually up to four. Higher stages will likely instruct you to repeat the polishing process multiple times while upgrading the pads provided or using a different compound. Most kits will recommend at least Phase 2. On lighter colored cars, stage 2 is fine. On darker cars or older cars, I recommend following the directions to the final stage. This will make the end result look better.