If you want to start street performing/busking for tips in your city, I would first recommend to check your city's laws and see if you need a permit that will allow you to do this sort of thing. After following those necessary measures, I remember picking a decent hot spot in my local downtown area where street performing was allowed and I just simply brought a top hat already slightly filled with a couple $1 bills, a few $5s, a $10, and just started performing my magic to anyone willing to stop and see. The hat was in a visible area of my performance so after the routine it was VERY common that I would receive a tip, even at least $1. I didn't necessarily ask for tips, it was just suggested with the hat already filled with some money. If you have your routines down, you perform them well, and engage your audience, they will likely tip if they already see money in your hat. Psychologically this will allow them to think "he already has a little bit of tips, he must be pretty good" and the probability that they will also tip goes up.
Keep in mind this is what I did when I was a beginner and had no prior experience to street performing. I was very nervous and scared to start, but once I fully committed to it and started performing a few routines, all of that went away and it became so much easier to go out there and perform. All it takes is to just start doing it. It's the only way you'll really know what you need to improve on!