1.    Don't start a layout without having a concept/idea.

Before starting, ask yourself: who am I designing this for? What are the target's preferences? How am I going to make this better than the client's competition? What will be my central "theme"? Would it revolve around a certain color, a certain style? Will it be clean, grungy, traditional, modern etc? What will be the "wow factor"?
Then, before jumping to your favorite part - laying everything out in Photoshop, right? - take a sheet of paper and sketch your idea. This will help you organize the elements better and get a general idea of whether an idea would work or not, before you invest too much time designing in Photoshop.

Do sketch the layout before laying it out in Photoshop.

2.    Don't obsess over the trends.

Shiny buttons, reflections, gradients, swirls and swooshes, grungy elements - all these are staples in contemporary web design. But with just about everything else, moderation is key. If you make everything shiny, you will end up just giving your visitor an eye sore. When everything is an accent, nothing stand out anymore.

Don't go reflections crazy

3.    Don't make everything of equal importance.

Egalitarianism is desirable in society, but it doesn't apply to the elements on your web page. If all your headlines are the same level and all the pictures the same height, your visitor will be confused. You need to direct their sight to the page elements in a certain order - the order of importance. One headline must be the main headline, while the others will subordinate. Make one picture stand out (in the header, maybe) and keep the others smaller. If you have more than one menu on the page, decide which one is the most important and attract the visitor's view to it. Create a hierarchy. There are many ways in which you can control the order in which a visitor "reads" a web page.

Do layout the design elements according to their hierarchy

4.    Don't lose sight of the functionality.

Don's just use elements because they are pretty - give them a legitimate place in your design. In other words, don't design for yourself (unless you are designing your own websites, of course), but for your customer and your customer's customers.

Don't make pretty things and then ask what you can use them for.

5.    Don't repeat yourself too much and too often.

It's easy to get tricked into reusing your own elements of design, especially once you got to master them to perfection. But you don't want your portfolio to look like it was created for the same client, do you? Try different fonts, new types of arrows, borders styles, layer effects, color schemes. Find alternatives to your go-to elements. Impose yourself to design the next layout without a header. Or without using glossy elements. Break your habits and keep your style diverse.

Recycling is good, but don't overuse the same elements

6.    Don't disregard the technology.

If you're not the one coding the website, talk to your programmer and find out how the website will be implemented. If it's going to be all Flash, then you want to take advantage of the great possibilities for the design and not make it look like a standard HTML page. On the other hand, if the website will be dynamic and database-driven, you don't want to get too unconventional with the design and make the programmer's job impossible.

This Flash website is not your usual standard layout. Check it out!

7.    Don't mix and match different design elements to please your client.

Instead, offer your expertise: explain how different elements look great in a certain context but don't work in another one or in combination with other elements. That's not to say that you shouldn't listen to your client. Take into account all their suggestion, but do it to their best interest. If what they suggest doesn't work design-wise, offer arguments and alternatives.

Don't throw EVERYTHING in the blender.

8.    Don't use the same boring stock photos like everyone else.

The happy customer support representative, the successful (and political correct) business team, the powerful young leader - they are just a few of the stock photography industry's clichés. They are sterile, and most of the time look so fake that will reflect the same idea over the company. Instead, try using "real people", or search harder for creative and expressive stock photographs.

Customer representatives are the happiest employees. Right?

9.    Don't try to reinvent the wheel.

Being creative is in your job description, but don't try to get creative with the things that shouldn't change. With a content heavy or a portal-style website, you want to keep the navigation at the top or at the left. Don't change the names for the standard menu items or for things like the shopping cart or the wishlist. The more time a visitor needs to find what they are looking for, then more likely it is they will leave the page. You can bend these rules when you design for other creatives - they will enjoy the unconventional elements. But as a general rule, don't do it for other customers.

Some things are better left alone.

10.    Don't be inconsistent.

Stick with the same fonts, borders, colors, alignments for the entire website, unless you have strong reasons not to do so (i.e. if you color-code different sections of the website, or if you have an area dedicated to children, where you need to use different fonts and colors). A good practice is to set up a grid system and build all the pages of the same level in accordance with it. Consistency of elements gives the website a certain image that visitors will become familiar with.

Don't make the visitors believe they landed on a diferent website every time they click a menu link