Twitter is a medium where people can see the 'real' you, so first and foremost you can create Twitter posts about your day-to-day life, actions and thoughts. I am not saying that you write a Twitter post every waking moment of your life or every blink, but when something worth tweeting comes up. This something can be humorous, or an insight into your daily life.
These tweets will reveal if you are nuts, or you have something in common with other people. I have found other people on Twitter who also get woken up by their pets nudging them, who can never find a comfortable pair of shoes no matter how hard they try, who prefer reading transcripts rather than watching videos and people who've I managed to help when I spot a question I can answer.
So the first thing you should know about Twitter Posting is to look at what people are saying. Yep I am giving you full permission to eavesdrop on people's conversations! So if you see a Twitter post that you'd like to comment on (even if it's addressed to someone else with an @) feel free to join in.
As long as you add something of value to a Twitter conversation it does not matter that you 'butt in'. When you add something of value, these people will thank you and remember you and maybe even follow you back, if they are not already. But at the very least you will have made someone take notice of you.
Try not to tweet a direct link to a salespage (or affiliate link), as this tends to lose you followers. You can be quite creative and get around this by saying 'Today I have been working on …', for example, but it is a little frowned upon, unless you are a guru. That's the great thing about Twitter, you can create your own rules and see how others react.
What I suggest you can do instead is provide is provide direct links to free ebooks, which have your sales links embedded into it, or to squeeze pages where you can also capture an email address before sending on the free ebook. This is basic Internet marketing really – you are using Twitter to get the traffic.
Another thing you can do is write good blog posts, Squidoo lenses, articles, knols, or whatever it might be and give links out to them in Twitter- you can also put links to your salespages in these mediums too, as this deemed acceptable.
By giving some value back to the Twitter world, the world will tweet about it! Word of mouth and Twitter go hand in hand and if you link to something of interest or is controversial, you can expect that link to be twittered and tweeted.