Twitter / Put your website URL in your Twitter profile, not just the URL field. This will allow more mobile users to click on your website.
Facebook / Did you know you can boost your Facebook posts to reach more people? This is especially good if you run a small business and want to promote your products. It costs as little as £3, so doesn't break the bank! Simply click on 'Boost Post' after publishing your post and follow the instructions. It's simple and definitely effective.
Instagram / Add text over your images using loads of free online editing tools, such as PicMonkey