This article could probably be called the 100 most deadly mistakes in website design--there are so many goofs site builders make--but let’s narrow the focus to the most disastrous 20. Avoid these gaffes, and your site will be far better than much of the competition.

Some websites are great, with a crisp, contemporary design that emphasizes usability. Some websites are mediocre, but if you are sufficiently motivated, you can find what you need or buy what you need to buy without too much difficulty. Some sites, well, suck, and even if they have good content or great merchandise, you’re outta there.

How about your website? Have you avoided the most common website design mistakes to give your visitors a delightful experience — or are they bouncing before they’ve even begun?

To evaluate your site’s effectiveness, download the 20 Website Design Mistakes checklist below (and read on for the condensed version).

20 website design mistakes

I’ve put together a handy checklist that you can use to score your website. Here’s what you’re going to be looking for:

1. Speed

Does the website load fast on every device, even on a mobile phone? It’s gotta be speedy. If your site is too slow to load, users won’t stick around and see your great content. If your page is slow to load, it might be lousy code, overly large images, too many external calls to cloud services, or an overload hosting company.

2. Responsiveness

Do things happen fast? When the user clicks on a menu or selects an action, the site should respond instantly. If not, it’s possibly a coding error. If you are loading active content, check the database and the database query code.

3. Intuitive

It is obvious what the user should do at all times? Make a list of things that the user might want to do on each page; it should be no more than five or 10 items. Is it obvious how to do those things? If not, fix it.

4. Text

Is it easy to read, and does it scale? Don’t use fancy typefaces — no Comic Sans, no Brush Script, no Avant Garde. Stick to standard system fonts. Use sans-serif for headers, and serif for anything that’s more than a couple of lines. Make sure the browser’s zoom function works on your text.

5. Text colors

It is easy to read? The best color for text is black. The best color for the background is white. Any other combination lowers usability. Give yourself zero points if you are placing text over a dark or black background – and make that No. 1 on your fix list.

6. Text heavy vs. scanning

Are you making your visitors read too much? Whether on a desktop, laptop or phone, people don’t want to read too much on your home page. Make the text brief and quick, so they can “scan” it — that is, take it in at a glance. Of course, if you are publishing articles, you’ll need to display lots of text, but not on your homepage or elsewhere on the site.

7. Obvious flow vs. hunting

Does the user know where to look? The content on your page should generally go left-to-right, and then top-to-bottom. (Unless you’re working in a language that doesn’t follow those conventions.) Put the most important information (or the most likely action items) at the top left, and take it from there.

8. Proofreading

Is the writing clear and well edited? Keep it simple, and get it right. If you have typos, missing words or bad grammar, your site’s credibility will take an instant hit. Give yourself two points if the person who writes the text also posts the text. Give yourself zero points if nobody else proofreads.

9. Elegance

Are there lots of white space? High-end stores have wide, friendly aisles. Junk stores cram things together. The same is true on your website: Use white space as a primary design element.

10. Annoyances

Are there pop-ups? Pop-ups and other interruptions are really bad for usability. Sure, some sites use them to sell ads, push subscriptions or otherwise get the user’s attention. You might have a good business reason to use pop-ups — but design/usability isn’t one of them. Give yourself zero points if you use pop-ups.

11. Colors

Are they light and helpful, or bright and garish? The colors used on a website should make the site more attractive, and not like an explosion in a paint store. Even if your site is for a paint store, don’t do it. If you don’t have good art skills, consult an artist with experience in web design.

12. Autoplay

Does your site automatically play music or videos when the home page loads? Shame, shame, shame. Stop reading this article and turn those features off. I’d like to give you fewer than 0 points — maybe 0 points for the whole questionnaire. By the way, I lump animated GIFs and any use of Flash into this same category. Get rid of them! Immediately.

13. Navigational simplicity

Do you have lots of deep menus, or just a few? Too many menus and menu options drive visitors crazy. It’s even worse if you have, say, drop-down menus and the same items replicated at the bottom of the page. Ugh. Don’t do it. Use the top nav section to give normal actions, like finding products. Use the bottom for corporate information, such as the “About Us” and “Contact” and “Privacy Policy” links.

14. Contact

Is it easy for prospective customers or business partners to reach you? Sorry, telling folks to tweet at you might seem trendy, but it’s rude and unfriendly. Unless you have a truly compelling reason not to do so, provide a phone number and email address. Web forms are OK instead of email, but in those cases, program the system to email the customer to confirm that the message was sent. Of course, make sure you get back to the customer right away.

15. Search

Does your search engine work, and does it provide the right info? That’s one of the failings I see most, a really terrible search engine. You know if your search engine is good or not, so rank yourself accurately. If you don’t have a search engine and it doesn’t apply (like you have a one-page website for your pizza parlor), score yourself a 5 because you shouldn’t be penalized.

16. Above-the-fold

Is it immediately obvious what your business is, and what the website is for? When people click over to you, they must make an immediate decision whether to stay or leave. Don’t make them scroll; don’t make them guess. If you’re a paint store or a pizza parlor, say so, right up front.

17. Timeliness

Is your pizza parlor talking about your Spring 2014 free wings special? Too many businesses forget to update their website — and that means all of it. Business locations that have moved, prices that are out of date. We recently visited a restaurant and asked about something on their web-based dinner menu — and they’d stopped making it years ago. Guess nobody told their web consultant.

18. Error handling

What happens when someone goes to an invalid URL or goes to a moved/missing page? If they see a nice error prompt that leads them to the right place, give yourself 5 points. A customized 404 Page Not Found message, 2 points. A default 404 Page Not Found message, 0 points. If visits ever see a Linux, Windows or content management system error message? Stop whatever you’re doing and get your web guru to fix your error handler immediately.

19. Special offers

Are you giving the visitor something motivational? Say you’re running that pizza parlor. Visitors are coming to find your location or hours or the menu, perhaps. How about a little coupon? Or an incentive like free nachos for joining your club? Never miss an opportunity to build loyalty. Score yourself honestly. Nearly every website should have some special offers or loyalty program, but if this truly doesn’t apply, give yourself 5 points.

20. Real-world feedback

What do other people think about your website? Ask your friends and customers what they think, or even watch them use the site in a focus group-type setting. Pay close attention to their comments and observations. It’s OK to ask questions, but don’t argue with them or attempt to tell them that they’re misinterpreting things or using the website wrong. It’s their feedback; accept it as it is. That doesn’t mean you have to make changes based on every criticism, but the best judge of your website’s usability and design are its users — not you, your friends, your family and your employees.

Pro Tip: Have someone else conduct the focus group, not anyone involved with company or the website, so as to avoid telegraphing agreement or disagreement with the customer’s comments.

Download the website design checklist

Now that you know what you’re looking for, bookmark this page and score your website. Be honest, and use this as a guide for seeing how you are today — and to determine what you need to do in order to improve.

By the way, I’m a writer, not an artist, which is why this list is more focused on readability than beauty. That’s OK. I’d rather have my site usable. Wouldn’t you?