Buffer – This one is the simplest and most practical for the purposes of promoting content since it will automatically try to share the content you pop into its feed to your social profiles at the most relevant time, maximizing exposure. The main downside they scaled back on their free plan so now you’re limited to connecting 2 or 3 social media profiles before they required you to upgrade. Regardless, it’s still very affordable and worth the $20 per month they charge.
Some ad platforms will ask more of your landing pages than others, when running ads. For example, AdWords is much stricter, when compared to Facebook. AdWords typically requires that you do not have a ‘thin,’ site that is designed solely to collect leads. Because of this it might be a good idea to focus on using Facebook or Twitter, to begin with.