1. use a heat gun or hair dryer as heating will make angles and round surafaces more managable and vinyl/sticker will be more pliable. heat as you or heat after to make corrections.
2. you can use a razor blade and make small vertical slits in parts that will be on a corner or round surface.
3. to get rid of bubbles or other issues stick a needle in it and push/rub the air out.
you can use a combo of them all as well