I am very interested how you can approach a total stranger walking around and talk to him/her and make it relevant to cards, im not saying its impossible, I personally think theres no good way, if you or anyone reading this has a line or anything, I really want to hear it.(PM it)
This is exactly the issue - you are asking for "a line" - you aren't approaching someone to say something relevant to cards...you are saying something relevant to life. It is not a line, or a script to get you there...it is being a real person. Life first, magic second. If you were to chat up that person like you would if you didn't have cards, then magic could easily become a topic and any prop would be fine.
I saw a guy do linking Hula-hoops (rings) at a video store and get a free movie...PINK HULA HOOPS! He killed. However, he just talked to them like he wasn't wearing 4 pink hula hoops around his neck, until they asked. By the time he told them why they were there, they already liked him.
I think the issue with most of you, is that you have little practice in social skills are talking to people without the safety net of magic. The solution to the issue has been given, I am not sure why this continues to be a topic that seems lost.
I LOVE that you think that doing something more "organic" like bill magic, would make a difference...umm, NO, it would just allow you to do some magic without asking permission. So, force it on them - but at least it makes sense. This issue isn't cards, the issue is that a young kid walked into by a store, where someone on their break (where they are to relax) was asked if they could be bothered.
Sure, doing something that surprises them is a great way to see if they like magic...but you will get rejected as many times by just DROPPING magic on people...and then where will you go?
Mike has stated the ideal, just as I have - let me spell it out for the stupids:
Think of it as sales - Connect as a human being...not as someone trying to push something on someone.
Trust me - the time will come where there is an opportunity for magic...this can be playing with your cards while you talk with someone about real world stuff...their job, how busy it is, what they are reading, plans for holidays...whatever...if they see the cards and ask - go ahead - if you can work hobbies into the conversation...go ahead. COMMON SENSE!
Don't treat people like "targets" - and realize people 99% of the time, will have negative perceptions of magic - so you are fighting an uphill battle. However, if you make them like you before magic is mentioned, now it isn't about the magic, but a relationship that supports your act.
This is performance 101 really...and the fact that this thread is alive shows how very little is known about this, and how ignorant you are for passing over this information the first time around.
READ! How about - DON'T WASTE MY TIME