For an impressive website try to avoid following common mistakes:
Poor browser compatibility: A good website is that website which is compatible with all the browsers. If the website will not compatible with all the browser, then it counts a flaw for a website, no matter how good other things are.
Large slow loading graphics: If the graphics are too large or take much time in loading them then the value of website will lower down. Graphics should be of quick loaded and too large so that graphics will load with the single click.
Multiple use of animated graphics: The multiple use of animated graphics, because it creates a confusion in the mind of viewer about the tabs and templates.
Too many graphics: There should be a balance between graphics, content and blank area.
Busy, distracting backgrounds: Distracting or busy backgrounds are a bad idea for the website development. Always try to use a background which flows with the theme.
Multiple banners and buttons: If you are using multiple banners and buttons, then make sure they are not confusing and directs to the right place.
Poor use of frames: Framing for pages of the website should be proper and accurate.
Pop up messages: If you are using pop ups on any tab then make sure all pop ups are working properly and open the same content which they are indicating.
Poor use of tables: Tablets used in websites should be direct to the right content.
Different backgrounds on each page: A website should have a theme and uniformity, do not use different backgrounds for different pages.
Over powering music set to autoplay: A mild music sounds good as a background, if music is powerful and loud then it will hammer the image of website.
Scrolling text in the status bar: The text on the status bar or footer should not be scrolled.
Too much advertising: With the load of excessive the soul of your website will gone somewhere so try to avoid too much advertising on the website.
Multiple colored text: If the theme not demands avoid using of multiple colors in the text matter because it breaks continuity of the website.
Multiple use of different fonts: Use some selected fonts for whole website, don’t use too much fonts for a single website.