A guitar (perferrably loud)
A case for said guitar ("Will work for weed" sticker optional)
Resources to get you to Europe
A hat (or two, if you want to wear one as well)
A guitar pick (if slapping your fingers on steel all day is not your idea of fun)
A capo, just to have one
An electronic tuner (this can be pretty useful, actually)
Learn three adjacent chords on the circle of fifths.
I recommend G, D, A for beginners because the fingerings are pretty straightforward, but you can chose whatever you like.
Commit all the words to Mr. Tambourine Man to your indelible long-term memory.
Googling "Mr. Tambourine Man tabs" will return a whole host of appropriate chord progressions. Pick one and learn it.
Travel to a mid-sized European city.
If possible, find a place where a lot of people speak English, but as a foreign language. This way, you will not only impress them with your realistic accent, but they will also recognize what you are singing. Furthermore, you won't have to learn a new language yourself. The city shouldn't be too big because then all the real street musicians come out and crush you. Of course, too small and there won't be enough donors. And why Europe? Well, on that lovely continent, you can scarcely bung a brick without hitting a cozy "metropolis" of half a million or so, and that is just about the target size for this operation of ours.
Find the crappy cross-eyed accordionist.
If in Scotland (that's not English they're speaking so it qualifies) you will probably have to settle for the crappy cross-eyed bagpiper. In any case, it is of the essense that he be crappy; before you go, you may first need to enroll in the course How to tell good bagpiping from crappy bagpiping at your local community college. Then again, I did but I'm still not quite clear on it.
Once you have established that the guy is actually crappy and not just pretending, sit down across from him and observe with interest.
This will force him to actually play different songs instead of repeating the same one over and over again. Presently, he will run out of material and leave.
Take out your guitar, lay down the hat, and begin to work his clientele.
Play as loudly as possible without sacrificing all semblance of tone quality. This will make you sound confident, which is a surprisingly important aspect. Avoid "rushing" as well, because it is a sign of nervousness and makes everything harder, anyway.
I don't advise making eye contact with anyone since people might think that you're trying to guilt them into donating. That never has a good effect. Just pretend that you are practicing your music in your own little world. (This, incidentally, is a great cure for nervousness too - if you can pull it off)
When you first learn the song, try not to look at either hand. Eventually, see if you can close your eyes and still play. This way, your fingers will remember the pattern even better, and it'll be way easier to pretend that you are alone.
In some cities, I imagine that you have to get permission to play. Don't bother unless you happen to know that there is a significant punishment for spreading joy and music around the world. Like the confiscation of a limb or large wad of cash. Better yet, find yourself a new city.
If an aspiring street musician tries to pull the same trick that you did on the crappy cross-eyed guy, don't worry. In the end, it really doesn't matter whether some people catch you repeating the song. I mean, what are they going to do about it? Wish they hadn't been so generous is what.
And that's just the thing; people take pleasure out of giving money to artists. I don't understand it but I do it with the best of them, all the same.
Oh, and if the C.C.B comes back with his kin, try to hypnotise them with rhythmic contortions and chanting. When that doesn't work, curse your rash decision to take advice from people on the Internet and succumb to the righteous beating which subsequently ensues.
People tell me I'm just jealous because I can't affect a Scottish accent or play bagpipes. Man, you guys are so right.