1. Lack Of Responsive Design

More than half of people use phones to visit websites so your site must work well on phones. If it does not your site will show the computer version which is hard to read and hard to use on a phone and people will leave fast.
You can use a tool like Google Mobile Friendly Test to see if your site works well on phones. To fix any problems choose a design that works on all screen sizes or ask a web team to help you make it work.
Make sure pictures buttons and words change size for smaller screens and are easy to click. A good example is MasterClass because it looks simple and nice on any device. Make a phone friendly version of your site and your visitors will be happy.

2. Difficult Navigation

Simple and easy-to-use navigation is the main key to a great website experience. But if visitors cannot figure out your site, they will not be able to find what they want and will just leave.
To eliminate this, have a structure of your website that makes important pages accessible and ensure that users can return to your homepage from anywhere on the site via the main menu or logo.
Check your anchor links as no one likes frustrated visitors visiting a broken link. Well-organised, straightforward navigation makes users want to browse around your site, and keeping them happy is key.

3. Weird Colour Combinations

If you are not a designer, then selecting appropriate colours for your brand or your website can become a hard job. It’s not only choosing the palette you think works well together, but also applying it correctly.
One of the most common mistakes is trying to use too many colours at once. Five colours in your palette do not mean five colours in every design.
So bright colours like red, yellow and green can look appealing on their own, but together they can be loud. Side by side, they can also conflict and red and yellow can end up looking like a fast-food logo or red and green can be too Christmasy.
TL;DR: not too many colours, choose wisely and pair them like a pro. The simpler and more thoughtful it is, the better it performs.

4. Slow Load Time

Visitors are easily deterred from a website, especially if it takes forever to load and this results in them closing your website in a few seconds. 
Users today expect websites to load within a matter of seconds, so if your site takes longer, they’re probably just moving on to another one. If your page takes longer than two seconds to load, it is time to pick up speed. Most users expect a page to load in under two seconds.
If your website is slow, simple speed test your site with the help of some tools like Google PageSpeed Insights, which also offers a few pointers on improvement. Compress big files such as images and videos. io, so that loading speed is significantly faster without the loss of quality.
Discord is a classic example of a rich media site that is nevertheless very fast, because the content is the only thing that is not weighted down by excessive page weight. When a website is fast, visitors enjoy their stay and stay longer to explore.

5. Difficult-to-Read Fonts

One of the biggest web design mistakes is selecting fonts that are very hard to read. If visitors are unable to read your text, they are not going to stay. Avoid the common mistake of font size, I cannot read too small or too big.
Fancy fonts can look pretty, but they are hard to read in long text blocks, so stick to a simple, clean font. Having more than 1-3 fonts makes your site appear cluttered, so be consistent with the font.
Also, resist bright od oversaturated font colors that will truly not be easy to read, black or dark grey is always a winner To solve these problems, keep your body text at a minimum of 16px, use high-quality sans-serif fonts such as Arial or Helvetica that are easy to read, especially on the screen and make your headings larger than the body text. 
Choosing the right fonts will help you create a simpler and more accessible user experience on your website.

6. Incomplete Website Design

Lack of Responsiveness A partly built web design will make your website seem untrustworthy and send visitors away. And if your site looks cluttered, has broken links, text awkwardly wrapping around images, or things that are just plain missing, people may assume your site is not completed or broken.
It can damage your business reputation. The Solution: Go through all your links and ensure they are functional and not directing you to dead pages. 
Make sure your site has a uniform design on all pages as it will make it refined and help you look professional. Employ white space strategically to balance and enhance readability, and give your site a feeling of order. 
Once you are done publishing, then check everything: images, text, buttons, to ensure that everything is looking fine and working well. An identifiable and well-put-together site creates trust between visitors and themselves to stay on for longer.

7. Unsecured Site

Many people are concerned about online safety, you need to ensure that your website is secure. Your site needs to be secure, otherwise, people will feel unsafe visiting your site, and they will bounce off.</span
And with online stores, this is even more critical in online stores, as people are not going to want to enter in their payment information if they feel threatened. You need to secure your site even if you are just storing names and emails to build trust.
Get an SSL certificate, notify the site that it should use “HTTPS” instead of “HTTP” and protect user data.
Also, implement other precautions such as unique passwords, maintenance of your software, and usage of a safe web hosting provider. The first thing a visitor notices is it is secure or not.