If you're using social media to build a brand (whether it be your business or your personal brand), you have to focus on creating value for your audience. Social media is where you connect, not where you close. It's that simple.
Create Value For Your Audience
How do you create value for your audience? It depends what your business is, but the good news is that it can be done in so many ways.
Here are a few ideas for posts a business could use for Twitter, LinkedIn, Google+ or a Facebook fan page.
A business providing a professional service could point people to a blog post that gives them tips or tricks for dealing with a common problem they encounter.
A retailer could share an offer to entice customers to visit - "10% off your purchase if you mention this Tweet - today only".
Why not have some fun with what you share on social media? A restaurant could post "First person to visit us and dance Gangnam Style eats free!".
An information marketer could point people to interesting content from people you follow or you give something of value away (e.g. an ebook or a white paper).
Whatever you're communicating, just make sure it's of value to your target audience.
The ways you can create value for your customer or audience are really endless. It all comes down to your creativity. And in my opinion, even making your audience smile counts as creating value.
Don't Do These Things
Repeat after me:
"I will not tell people to check us out on Pinterest/YouTube/Wherever".
"I will not tell people to go and like my Facebook page".
"I will not tell people to buy my [insert thing that you sell]."
"I will not..."
You get the idea. Don't tell people to do things on social media which serve you and the benefit to them is unclear.
You need to first give people a reason to do something, by offering them value, and then you can tell them where and how to get that slice of awesomeness.
The opportunity to connect with you on different social media doesn't in itself provide value for your audience. Focus on the thing that provides them with value, and then tell them where to get it (which may be on your web site or another social media site).
Once You've Spread The Love
Can you make a sales pitch using social media? It depends on whether you've first provided value to your audience, and how you deliver your sales pitch.
If you've built trust and provided value, your audience will be more likely to reciprocate. I think it's reasonable to use social media to start a sales pitch, but I don't recommend going straight for the close.
Your social media post could arouse curiosity to get your audience to click on a link that takes them to a one-off sales page, or perhaps an opt-in series where you could first offer more value before directing them to a sales page.
But the social media post itself should not be so blunt and say 'click here to buy my ...'.
A Few More Things to Remember
When communicating through social media, you want to keep a few copywriting principles in mind. Given the limited space, I suggest focusing on headlines and calls to action within your social media posts.
If you focus on the common elements of effective headlines you can't go wrong:
Appeal to the reader's self interest - offer them a benefit
Arouse their curiosity in the reader
Shares news or information that they would value
Offering a quick and easy solution to a problem they have
Also remember to write with a simple and clear style, and ALWAYS include a call to action.