Choose Best Host
Don’t use Shared Hosting. If you Use, your Site Speed Frequently Down during high traffic periods. The stress of your site going down after getting a big feature, Invest in Proper hosting.
Choose Best Theme
In terms of speed Themeforest Themes is Best.
Use Best Caching Plugin
I would recommend W3 Total Cache caching plugin.It has Best Features. With this Caching Plugin your page load faster.
Use Optimized Images
In these Days Images are the Best Part of Your Website. Use Clear and Optimized images to speedup your website.
Optimize Your WordPress Database
I would also recommend the WP-DB Manager plugin, to optimize database.
Adjust Gravatar Images
Gravatar Images Speed up Website.