Be aware of responses to your 'excuse' touching - if you've tried this several times and the other person has not returned these touches the chances are they are probably not interetested in taking the relationship to the next stage.
If you are interested in the person who is 'excuse' touching you then make sure you respond if you're interested. Don't convinvce yourself that you've imagined it and not return the gesture otherwise they will think that you're not interested and back off.
If they do not want to take the relationship any further they will not respond and the relationship is likely to remain platonic.
These touches allow you both to feel confident in your attraction to each other and you can then make your 'first' move, the kiss.