With practice, you will be able to judge the size of beads thus avoiding squeeze-out and the subsequent need to clean up.
Uncured sealant can be removed with a clean, dry rag and any excess then removed with a cloth lightly dampened with mineral turpentine or white spirits. Excess cured sealant is best removed with a plastic spatula to avoid damage to the surface finish of the metal.
Avoid any unnecessary smearing of sealant on surfaces intended for painting as silicone can affect adhesion of paint. Smeared sealant may be treated by lightly abrading the area with a non-metallic scouring medium.