Okay, you know how you only use ten percent of your brain? That's because the other 90 percent is filled with curds and whey.
-Todd Ingram, Scott Pilgrim vs. The World
Vegans are great aren't they? We have great hair, psychic powers, and immortality on our side, so it's hard to believe that anyone isn't one.
The fact is, there are a number of benefits to vegan living, but if we inflate any of those benefits by even an extra adverb, we're shooting ourselves in the foot (not vegan!). Many people are already skeptical, and if you give them a little bit of inflated or incorrect information, they're going to dismiss everything you have to say.
So before you launch into your lecture on the health and social benefits of a vegan life, take a breath and remember: Veganism doesn't need you to make it better. It's already the compassionate choice. The diet already has the potential to be health-building and nourishing (I say potential because you could technically be a vegan consuming only Sprite and Fritos). So stick to the facts and be confident.
If anyone challenges you on the health benefits, you'll be prepared to answer them without sounding like you're off your nut, and the people you're speaking to will be much more receptive to new ideas.
That's not to say you shouldn't include your personal experiences. In my case, I feel more energetic eating a plant-based diet, and my seasonal allergies improved greatly when I gave up dairy. I also noticed a huge improvement in the condition of my skin when I gave up processed soy products. These are correlations that others have noticed for themselves as well, but I'm still careful to frame these claims not as scientific fact, but as personal experience backed by evidence.
I'm also not afraid to correct people who make outrageous claims. I hear things like "These chocolate chip cookies are healthy though, because they're vegan" or "You're thin because you're a vegan." Vegan cookies are still just fat and sugar, and my size has a lot to do with genetics and exercise. (Interestingly, it's always been the non-vegans that have made these claims).
However, I have heard vegans make claims that have little or no truth to them. I don't think vegans lie on purpose, but I think they get caught up in all the information that's out there and sometimes forget the difference between a reliable source and a person who happens to have an internet connection.
The fact is that wildly misinformed people aren't making it any easier for veganism to become mainstream. It alienates people, and for a good reason. It actually could be dangerous to you to assume that veganism is a cure-all that will prevent all disease and guarantees a fit and healthy body. AS a person who spent a few years subsisting on Chik Patties, Oreos, and Dr. Pepper, I can assure you that "vegan" is not a synonym for "healthy."
Something doesn't have to be magical and perfect to be worthwhile. Veganism will not end all injustice and cure all of your personal woes, but we'll win over more people by acknowledging that than we will by denying it. Build a strong base of knowledge and take good care of yourself. Know nutrition inside and out, and be excited to truly understand the way the body works.
So how are you going to learn your vegan health facts? By reading up at the Vegan Health Page.
It's important that you can convey accurate information to others, but it's also important that you take care of yourself. We'll have no pity for you if you quit because your all-Frito diet left you anemic.
What about presenting solid, evidence-based reasons for going vegan? Health is a great place to start because it strikes at what all people love best - themselves. But many people go vegan for bigger reasons. You can read about them at Compassion Over Killing's Try Veg Page. You know why, but make sure you really understand why.
If you're old-fashioned, or just really like books, check out Becoming Vegan, The Vegan Source Book, and Vegan: The New Ethics of Eating. There are, of course many other great books out there, but this is a jumping off point.
Keep in mind, you don't have to know everything. No one person has a responsibility to be a walking encyclopedia of vegan knowledge, but it's helpful to have a solid foundation. Actually, knowing where to look is just as, if not more, helpful. You can brush up anytime and direct others to resources, providing them with multimedia learning tools.
It is imperative that you give the best, most accurate information you can. Never be afraid to say "I don't know" or even better, "I'll need to look into that to give you a good answer." It's infinitely better than providing an answer that might be true, or that you seem to remember reading on a forum somewhere. Make sure that your claims are substantiated and your efforts to reach out to people on the behalf of animals will be strong and effective.