are you extremely knowledgable or are you just upset that you're alone and want to rain on someone else's parade? Telling people to "give up" is pretty much the worst advice you can give. Just because you've had bad experiences does not mean that everyone will. I've had bad and good experiences from approaching people, it's really a gamble, but if you don't take it, you will never meet anyone, you'll never get into relationships, and well, you'll never stop being alone.
Also, flowers? what is this, the 50's? In modern times, anonymous bundles of flowers cause way more confusion than admiration. That happened to me a few times and I threw them away. I still don't know who any of those flowers were from and its pretty annoying.
I know its really hard, I'm one of the biggest fools on the planet when it comes to randomly approaching people, but saying something simple like "hey, what's up?" usually works, even if for friendship.