Unreadable sites often contain flash that isn't recognizable by search engines
. Flash might seem impressive to visitors but probably not to search engines. Flash won't help optimize your site at all. So if you want to actually get search engine traffic, then you should create a plan HTML alternative on your website if you really want to use flash. Make sure this HTML page has lots of written content with the appropriate keywords so that the search engines know what to rank your site for. Getting your entire site indexed by search engines is detrimental to the success of your site.
Your ratings will be better if you create content on your site that is appealing and interesting. Similarly it's a mistake to have bad content on your website because even that won't do any good to help it rank better. Your focus and determination will show in how well your content and theme go together.
If your keywords are horrible your content will suffer. Search engines look for content that is useful and relevant to your targeted niche. So if you are able to offer them targeted information, in an organized way, then you can definitely expect to rank well. Your rankings will suffer if your site links to irrelevant information.
Keep your content on one domain name. It is necessary to avoid using multiple domain names and sub domains except in certain circumstances. Using multiple domain names is often misconstrued as a way to dominate the industry. Put all of your attention on your first page to increase the traffic and ranking of that site, this will reap better results. This will slowly turn your site into an authority site that everyone looks up to.
Using more than one domain or sub domain is not likely to increase your ratings so avoid it at all cost.
These are some of the SEO mistakes that can ruin your efforts, so make sure you avoid them when planning your campaigns.