Let's assume: Your audience wants to share your post. Your audience may love or loathe you, but either way, they want to tell others about your post.
Here are some of the basics -
1. Enable sharing buttonsThese are the buttons at the bottom of each post. This lets your audience share individual posts. Why not just give them the URL of your blog? Because the post they may wish to share may have been published months (even years) ago, so the URL of the post will be www.myblogtitle.blogspot.com/thispost-is-amazing-you-should-read-it and not www.myblogtitle.blogspot.com. As you keep blogging, you will find that you have posts in your archive that are popular and as your audience grows, this is the one that they may want to share.
2. TweetYou don't have to become a mad-keen tweeter with tens of thousands of tweets, but do us a favour and at least have a Twitter account that you check at least once-a-week.
Why? Think about it. Where do we "share" your posts? On social media platforms. I would like to be able to simply RT your post rather than wait until I get to my desk, then copy the URL and paste into Twitter (and Facebook and G+). Even if your Twitter presence is a broadcast presence, it's better than nothing. Oh. And make sure you write in your Twitter profile, the URL of your blog*.
3. Have a Facebook Page for your blogSee above. But remember, have a Page and not a PROFILE. I don't really want to be your "Friend", I just want to subscribe to your posts.
4. Have a G+ page for your blogSee Twitter and Facebook above.
5. Enable the subscription widgets/gadgets that are availableYou don't know how people will wish to subscribe to your blog. I subscribe using lots of different methods - Facebook Pages, Twitter Accounts, Google+, Google Friend Connect, G+ Follows.
I don't use one method because each blogger has different subscription methods. So, the very least you can do, is to offer up a couple, even if it's just the default ones available on your platform. You don't even have to put them in the sidebar (and fill up all your real-estate), you can often put them in the footer.
6. Start an Email NewsletterWhen you're really deadly, offer a weekly or monthly email to your audience. For a lot of the professional bloggers, an email newsletter is one of their key marketing tools. If that's the space you're going to play in, you should give it some consideration. You can sign up to a freemium (free for the basic membership) newsletter service like MailChimp, and see how it works for you.
Behind the scenes, I do get asked for advice, and seem to have a bit of an "advice" column that lives "off-the-wall". If you have any questions, ask away and I'll see if I can help.
Any other subscription methods I should include in this post? Let me know and I'll add them to the list.
* As silly as it sounds, I wouldn't have written this, if it didn't happen.