Out of so many templates you need to choose one, but the point is which one? There are some factors which will help you choose the best design for your website, a design is not what you like or what you want, a website choose a design itself for the Quality of Audience and people who are targeted, just to be obvious, what do you expect a design for a porn site? it can't be simple and professional. Choosing a design for your site is like reading a mind of your visitors, seriously you don't need a web designer but a psychologist to guide you about what colors your audience will like and be attracted.
1) Niche of a website
Basically Niche of a website means type of audience, their activities their like their behavioral aspects, i will use few specific examples to be clear enough about the this factor, lets take an example of Photography,
Generally websites like photography need to be really very professional yet Bold colored and with huge pictures and dark backgrounds and a high Quality pictures with galleries and sliders, so the target won't be to Load the site quickly but to put lot of high Quality pictures and content in it. On the other hand lets take an example a website of Doctors, it need to be really plain and its better that it uses light colors really calm which makes it simply professional no blinks no animations no high colored pictures no high contrast Graphics, overall the website should be covered with almost 60% white.
So the niche of a website is really dependent on the design you choose, if the reason is to entertain then site should be bulky heavy animated with so much upfront, but if it something serious then better be simple.
2) Choose a Color Scheme
Once you decide a color then you might need to know before applying that how the combination should look like, i found a very helpful tool for such thing known as "Color Scheme Designer" which can be find here it will help you choose the best scheme for your site using different schemes, Generally dark background colors are risky and light font colors are annoying this one annoys me. and this background color is worst. if combination of colors are not selected wisely, but at the same time black background with white color font also look good.
The Most important part of your website design is Layout, how to decide how many sidebars you need and what should be the width of your content area, that depends on the content you have on website, if your site consist of just 5 to 6 pages then you don't need a sidebar, but you can use sidebar to add contact us info, phone number or something so in that case single sidebar would be enough.
Basically sidebar is the extension of top menu, your target is that visitors are able to browse navigate whole website just from front page and if you got lots of content i.e your website is related to News then you might need 2-3 sidebars and narrow content area. so layout is dependent on the Quantity of data a site holds.
Combination of these 3 Factors decide a best Website Design, if you want to add anything feel free to write in comments.