Design and User-Experience
Certainly, your reason for choosing a particular theme is to make sure that your website would look impressive and your brand would be displayed in the best way possible. You can find a theme that suits your business by following a number of steps.
As a start, search for the sites where the best-designed themes are sold. Though this may be obvious, I find it worth mentioning. My personal favorite is Theme Forest but there are also lots of good designs available in Elegant Themes and Studio Press.
Next, devote time to browse the demo. See if the website looks simple to use. Does it have enough white space? Does it feel exciting or does it give you a headache? Your gut feeling plays a vital part in the choices you make.
Lastly, choose a cross-browser compatible theme, which has also been built to be accessible.
Responsiveness
Mobile traffic differs from one industry to another, but many reports have come to an agreement that on an average, 30% of people use their mobile phones and tablets in visiting websites.Whether or not this is accurate, there is more than enough reason to use a responsive theme.
Nearly all reputable themes are compatible with mobile devices, so when a theme lacks responsiveness, this is a cause for concern. Many theme sellers allow you to filter out unresponsive themes. An additional option is to browse over a curated, responsive theme list. One of the effective ways to know if a responsive theme is good enough is to try to run the demo via Google’s latest mobile-friendliness tool.
SEO
When WordPress is equipped with any of the several great SEO plugins, it could be among the most SEO-friendly CMS available. Yet, a lot of themes make all kinds of on-site SEO errors like omitting header and alt tags, duplicating content and making dynamic URL mistakes.
In choosing a theme, go for one that mentions “SEO ready” or “SEO optimized” in its description, but do not blindly trust it. Many developers add this so they could sell their theme. When you know that a designer has at least taken SEO into consideration when developing their theme, you get some sort of assurance.
You can install an extension like SEO Site Tools or Mozbar for the Chrome browser to do some fast SEO checks on the demo of a theme.
Easy to Customize
Several themes come standard with a customization dashboard. This way, you don’t have to do direct changes to style sheets. Furthermore, plugins like Visual Page Editor simplify building complicated page structures without the need to touch code. A number of these WYSIWYG editors are quite limiting, but overall, I consider them as very advantageous to making a website look impressive without exerting much effort. If a demo of the developer’s administration panel is available, I would suggest you to try it so you can customize the things you need to.