A lot of themes come with built in social sharing icons these days, but they usually add the kitchen sink. It’s often not advantageous to use every site – that’s too many choices. Stick with Twitter and Facebook. MAYBE pinterest or LinkedIn, or G+; if those are platforms you are actively using.
But too many choices is worse than not enough. Make it really easy, with just a couple choices.
And ask them to share your content.
An easy trick: Ask them to think of who they want to share with first.
Can you think of anybody who would find this useful? Be kind and send it to them!
Make it about them and the people they want to help. They shouldn’t feel like they’re doing you a favor. I usually use them at the end of every post. Some people like them at the top. They might need to be on your category pages (like your blog homepage, if you’re showing excerpts and not full articles… except I think that slows down your site too much).