It can be a time-consuming and difficult process to find the right WordPress Gallery themes for a blog, website, web shop etc. One of the best things about WordPress is its openness and flexibility that have invited thousands of skilled designers to create awesome themes for the platform. This is one of the benefits WordPress offers compared to other major open source CMS platforms like Joomla and Drupal. The huge availability of both free and premium themes for WordPress makes it a challenge to find the suited theme for the site you are building.

A good place to start is to decide if you are willing to pay for the theme. In some cases this pays off long-term when you need support. E.g. when WordPress needs to be upgraded. If you have a little bit of design experience it is recommended to find a good theme and make some changes yourself. This model works for both a free and premium themes and is a cheap way to get a unique design for your blog or website.
From what I have leaned over time I believe the following steps are worth thinking through before picking a theme:
1. Does the theme have the flexibility you need? Flexibility is key when you startup a new site with gallery style but also when needs change over time. Normally it is important that the theme comes with a genuine "Options page". Having a theme with a powerful options page will keep you from digging into the code for just doing simple changes everyone have to do. A theme with short-codes, page templates (gallery and portfolio is important) and multiple color schemes also keep you from coding in most cases. As you can understand it simply opens up for the possibilities and allow you to create a unique online presence.
2. How will the website or blog's design affect your success? For a personal blog or website having a branded look is probably not that important. Again a free themes will do just fine. Websites or blogs created for a company are different and really need to stand out. Keep in mind that the look and feel of your website is critical for building your online brand.
3. Is the template you consider used by many other websites? It is worth noting that several of the more popular free themes are used by thousands of blogs. Logically this makes it more difficult to stand out, but occasionally it also has benefits. Some of the most used themes (especially premium themes) are supported well, and if you have a problem it can be easier to find assistance.
4. Is the theme SEO-friendly? When choosing amongst free themes you have no guarantees! Rating the SEO capabilities of a WordPress theme isn't simple unless you already have the files and have good skills in SEO, PHP and HTML fairly well! If this is the case you should choose a premium theme from one of the leading theme vendors or if you want a free theme pick one of the large and popular ones
5. Making money from a site is indeed out times great opportunity, but is this your goal for this website? In this case it is a good idea to go for a premium theme. They are usually implemented on mature frameworks and comes with support that can be critical when WordPress needs to be upgraded. If not, a free theme should do but consider a free theme form a premium vendor. The good thing about WordPress is that you can change the theme later.
6. How does the theme match your company style, logo and your customers? With free themes it is not always working well when a logo is added to the header, even though everything else about it is perfect. Keep this in mind and select the theme to match the logo you have making sure that style, colors etc. fit together.
7. Will the theme support widgets? With widgets added to the right locations in your theme it is very simple to add and manage non-post and page content like sidebar, footers etc. I recommend you look for themes with many widget zones as you will need the flexibility sooner or later.
8. Is support available? Support is critical if you are not a technical genius yourself. Any upgrade of WordPress may require updates in the theme and trust me - keeping WordPress updated is so important for security reasons. In some cases advanced and even simple things break and then support is so important to keep your site safe! Most of the larger premium theme vendors provide high quality support and have a strong forum and community. As a rule of thumb free themes does not have any kind of support and there is not guarantee it will be maintained. If you think you might need support somewhere down the road, take this into consideration. If you are familiar with themes and feel comfortable solving your own problems, don't worry about support.
9. Is the theme prepared for monetization? If you have any thoughts or intentions of monetizing your website or blog you should take this into consideration when choosing a theme. If it is part of the strategy, adding ads to a theme is simple for a web developer, but for most people it important that the theme comes with an ad management solution. Themes with a build ad management solution has also been prepared for it in the design.
10. Does the code validate? Having a website that validate is highly recommended, but most people don't know about this. Valid code e.g that follow the HTML specification, will give you the best chance of giving your visitors a problem-free visit. While users may not notice validation errors I can assure you that search engines will.
While it is impossible to know exact impact in search engine rankings coding errors is not going to help you rank better. In fact recently Google updates to their ranking logic means that they take a lot more factors into consideration than earlier.
11. Is the theme developer a generous and skilled developer or...? Does the theme contain hidden links, bad code (back-doors, file up-loaders etc.)? You might be surprised how many free themes include some form of hidden links to build back-links to sneaky marketers sites. If you are not sure how to look for hidden link then consider using one of the more popular free themes or even premium theme.