Okay, here is my thoughts, but keep in mind - I'm from Canada so my cultural bias is very much at play.
In a restaurant, it is different than busking "Hey if you enjoyed the show, please consider dropping some money in the hat"
If you approached a strangers and did street magic for someone and asked for a tip, it would seem like you were homeless.
For me if someone approaches me, they should not ask for a tip. If I approach them, then I expect to tip them. And if they are not good, and ask outright for a tip - that's awkward. People hate confrontation so they would likely leave a tip, but it would sour them to the restaurant and that's NOT your goal!
In a restaurant, I personally would never ask. I would worry that it would be rude or at the very least, tacky.
So, I would go for a more passive approach. I remember Paddy used to say that he had a small button that he wore that said that he accepted tips. I can't remember who said it but they talked about doing magic with a borrowed $5 or $10 bill. This get's the money into view. Then he said, instead of handing it back to them, set it down in front of you a bit far away from the person who lent it. He said it look like you are saying tank you and giving it back, but it's far enough away that they look a little greedy if they reach all the way across the table for it, so they often just leave it there. Then once you are finished, and saying your thank you, they will often just offer it to you. Not sure if that works, but it's subtle enough that it's not rude, and they feel generous because they are offering it. Is it manipulation? Yes. Is that bad? Not any worse than advertising imo. They also said something like shaking their hand and as you leave make it look like they gave you something and put it in your pocket - so that other tables will think that they tipped you. Not sure if that's necessary or not.
Another thing is that in 2018, people probably don't really carry cash. I don't carry cash, so how awkward would it be for someone to come up to me - perform, then ask for a tip - and I can't - even if I wanted to. Then if they were to say no problem and whip out a square reader, that would be so awkward.
So if I woke up in your shoes I would:
- Be so incredibly nice
- Be as funny as I could be
- Be humble and avoid any sort of arrogance
- Be thankful and appreciative of them and their time
- Be excellent at your craft!
- Accept tips with thankfulness
- Make your participants feel great about themselves
- Do magic with money that you want to be tipped with
- Do magic that leaves them with a souvenir
- Remember who tips. Adults. Not teenagers, not really young adults, but adults - and usually men (I can say that I only once received a tip from a woman - and she was flirting). Make eye contact with them, thank them, make them laugh, and they will be the ones to reward you. So if there are kids at the table, do magic for them, then something cool for the older guy at the table.
- After killing it for the restaurant for 4-6 months, enter into a conversation with the manager to see if things are going well and about getting paid hourly. If they can't then you can look elsewhere.
- Keep looking for other restaurants that will pay you properly. You can work multiple restaurants at the same time.
- And just be authentic. Treat them how you would want to be treated.
- Evaluate your audience. When it goes really well - why did it go well? If they tip, ask why do you think they tipped and the last table didn't? Did you say something? Is there a pattern? What were the ages? Why where they out for a bite to eat? etc.
- Carefully craft the script you use. Words are extremely powerful. Use words like ' tip, money, give, generous, thank you' etc. often. Example (in an aces to pocket routine) "Hey I have a good tip for you, 'when you are playing cards with a magician for money, don't assume they keep the aces up their sleeves, but rather in each of their four pockets'."
Don't leave this gig! Every opportunity that you have to perform, take it! Use this time - even if the pay is low to build your chops for the next place. So good job on getting the gig. That's the part most people don't make it to. You will love it. Restaurant magic is awesome.
Break a leg!