Make sure you find and fix these before they cost you traffic or give a bad impression of your site / business.
1. Responsiveness: Your website needs to look good and be functional on devices with smaller screens like Phones and Tablets as well as larger screens like Laptops and Desktops. *
2. Non-Adaptive images: This goes hand in hand with number 1. You don’t want your site to respond to different devices and screen and not your images. They will look distorted and ruin the whole layout.
5. Spelling and grammar: You can have the best looking, most responsive site around and totally ruin it with bad spelling and grammar. Remember, spell check does not always catch grammar errors. Proof reed (<-error) your content multiple times before publishing it.
6. Testing before publishing: It is easy to make a mistake in not only spelling or grammar but also your code. Just like proof reading in number 5, you should test your site a few times before going live.
* You can test the responsiveness in most modern browsers by shrinking the window. Chrome, Firefox, and IE will change your view based on the window size. If the site does not adapt, it is not responsive.