If you are a musician and you make your money from music–recordings, live shows, merch, etc.–then people have to LOVE your music. Period. They have to love it enough to decide to spend their 10 bucks on your CD or 15 to 50 bucks on a ticket to see you live. They have to want it more than a new Rock Band drum kit. Or a nice sushi dinner. Or a Twilight book. Or the latest music from Beyoncé. Or Sgt. Peppers from The Beatles, for that matter. It just isn't enough for the audience to think you're funny or even for them to like your single. They really have to love the music enough to sacrifice those other things to get it. And no amount of Twittering, blogging or YouTubing is gonna change that. Nor will the perfect brand strategy, a brilliant marketing campaign or even a total understanding of your audience and the permission to deliver the ideal message directly to their inbox.
Now don't get me wrong, all that stuff is necessary and deserves your time and attention because it gets the music in front of people. And if they don't know about your music, they'll never even have the chance to love it. But the only thing it buys you is a chance. It gets them to try it. In the advertising world, we have a saying, "Nothing kills a bad product faster than good advertising." And it's true. If a great ad makes you try a new frozen dinner and it tastes like hockey puck then the product is dead. And if your Twitter gets folks to listen to your new record but it makes them wish they'd been hit in the face with a hockey puck, then your record is dead, too. What's even worse is that it doesn't even have to be bad music. Even if they like it but don't love it, it just isn't enough.
So don't ever forget why you're here. You are a musician, dammit. Make great music. Play it for anyone who'll listen. And sure, you should talk about some personal stuff and be funny (if that's your thing) because it gives the audience context and opens them up to the music. And it starts to transform loving a song or two into loving an artist, which ultimately gets you more chances (hence, Garth Brooks' career didn't end as Chris Gaines). And it's the only way you'll build a career. But ultimately, who you are is merely context for the songs. And if they don't love the music enough to buy it, then you can't afford to continue making it.
So you've always gotta bring it back around to the music. If you want to build a career doing what you love, budget time for marketing stuff (press, social networks, videos, blogs, etc.) and have fun with it. But, especially in the early days, spend less time selling and more time creating something amazing that people will fall in love with and talk about and take into their lives as their own. Write better songs. Practice your guitar. Book more live shows. Start with great music and build the brand around it. Because, in the end, a brand is only as good as the product behind the label.