Know your target market
Rather than focusing on the development of your website, you should first search your target audience in your particular market. Then, you should develop your website around your research. If your product is geared towards younger demographic, then you should think about catering your site to be smartphone compatible.
Design is too flashy or busy
You should avoid using designs which are too flashy as they do not look good on tablets and mobile phones and most of the people these days visit websites from these wireless devices.
Paying too much or too little
You never know how many times people visit to the company after they have hired a cheap designer, let them make some important decisions that are poor and then they ended up with a product.
Using out of date content
Many customers expect your website to contain latest information about your company, products and services. When it does not have this, you can assume that you are not in business any more or are not innovative and you are ahead of competition. Your content must address different needs of your customers and it must be updated as things change.
Targeting everyone
It goes back to knowing your goal and your target market, your website will not be the way you want it to become if you try to cater every kind of visitor into it.
Excessive advertising
Advertising is important especially on blogs where it is considered as one of the main sources of income. At the same time, too many ads or flashy or noisy ads will frustrate your visitors and make you lose some money as well as business.
You should avoid making mistakes if you are working on low cost web development and you should also take the advice of professional web designer for avoiding any further mistakes.