You shouldn’t tell a girl verbally that you want to kiss her before going for it. It ruins the moment. It makes you come off as though you lack confidence by playing it too safe. If you are worried about whether you should go for a kiss, observe her body language beforehand.
A girl that wants you to kiss her flirts with you as you talk to her, enters your personal space on multiple occasions, and makes sustained eye contact with pupils that are often dilated. All these body language cues let you know that you should go for the kiss.