First off, let me assure you that anyone who promises you "guaranteed top 10 results", "submission to 20 000 search engines", "instant results", or "permanent top positions" is most likely a scammer. There is no way that anyone can guarantee that your page appears at the top of any search engine's results unless they actually control those results, or, naturally, if the top ranking is for a word or phrase that only exists on your page.
What has been shown to be very important as far as SEO is concerned are good, valid content, accessibility, usability, and high quality markup. This is a fact: If you make your site more accessible and usable for humans, you also make it more attractive to search engine robots.
Be very wary of firms that 'promise' or 'guarantee' results. If they suggest any dubious or suspect methods, be very careful - they may actually get you penalised by some search engines, or even banned!
So, here are a few important pointers to bear in mind when optimising your pages:
Firstly, there are no shortcuts!
There is NO quick and easy way to get results. You will need to do some hard work on your site in the beginning, especially when it comes to content. You will also need patience. Results do not come overnight!
Write good content
This cannot be stressed enough. The search engines' business is to point searchers to the most valid content that applies to their requirements. They LOVE to see valid content, useful information, and plenty of it. Your site may be technically ideal for search engine's robots, but it won't help in the least UNLESS it is full of valid content. Content is King! The content needs to be as specific to your business as you can make it, and as unique as you can make it. If yours is the only site in the world selling absocanthusblingblings, then you are virtually guaranteed a top spot! And your content needs to be USEFUL.
Good content will encourage return visitors. Those return visitors who like your content will eventually link to your site, and having plenty of valid inbound links is what search engines love to see, more especially if those links are from sites that have similar content to yours, and themselves are well ranked.
Almost as important as good content is renewed content. Search engines love sites that give visitors reasons to come back! By adding or changing content regularly, you encourage return visits, and search engine robots will also be more inclined to visit your site more regularly when they see that your content is ever-changing.
Creating quality content - or creating any site content at all - is rarely the responsibility of the web designer, however - it is usually up to the client to write their own copy.
Spelling, punctuation and correct grammar is important.
Notwithstanding the fact that American and British English spelling does vary, it is vital that the spelling, punctuation and grammar use is correct on your site - Often the site is a visitor's first impression of your business, and first impressions last!
Write descriptive page titles
Your page titles should be simple, descriptive and relevant, and by doing this you make it easier for search engines to know what each page is about. Also, people scanning through search results can quickly see whether your site contains what they are looking for. The page title is also what is used to link to your site from search result listings.
The title element is thus one of the most important elements on a page - some would say that it is the most important element.
Textify your graphics
Search engines cannot 'read' graphic content, but they can read text. If you use a lot of graphic images or titles, then use the images 'alt' tags to identify the images descriptively with text.
Get linked
Try to get as many inbound links to your site as possible, from reputable sites that contain similar content. This may sound easier than it actually is, but there's no doubt that if your content is good, if you are offering good value to visitors, then other sites will want to link to you.
Incoming links are very, very important for SEO, and also possibly the most difficult aspect to implement.
Make your site easy to navigate
If your site is easy for a human being to work through and understand, it will also be easy for search engines spiders to navigate. Your menu system must be logical and well-structured, using as much plain text as possible in the links.
What about Flash or Java sites?
Flash and JavaScript are all well and good provided they aren't required to navigate your site or used to access vital information. Don't hide your content inside Flash files or JavaScript. Remember also that flash sites will be generally slower-loading (and therefore more irritating to visitors) than plain HTML pages. They also tend to use up more of your precious bandwidth (and logically your visitor's bandwidth too), and so you will find that many visitors are not too keen on visiting such sites.
Submit to Google or not?
This is a moot point with web-designers and SEO experts. Should you tell Google about your site, or should you wait until Google finds you? There are those that hold the opinion that it is better to wait, and those who claim that it doesn't matter one way or the other. Submitting a site to search engines can be useful, especially if the site is new, and in my opinion go right ahead and submit to Google - It probably won't hurt a bit.
Don't try to fool the search engines
This is important - don't use cloaking, link farms, hidden text, keyword stuffing, alt text spamming or other suspect methods. There is a risk of being penalised or even banned from search engines - not your main aim at all. Search engines are in the business of providing accurate answers to searcher's requests, and they want their results to be valid and to-the-point. They don't like it when people try to trick them.
Avoid using frames
Frames are a rather old-fashioned way of positioning objects on a page. Frames can cause navigational problems when linked to from an external source, so rather use CSS in structuring your pages.
Meta-Tags - to use them or not?
The use of meta-tags to place key words within a page was certainly once a very valid SEO practice, as all search engines used them to some extent. That, however, is no longer the case. Most search engines today don't place too much value on meta tags anymore, since they have been abused by spammers. Certainly continue to use the meta description, but using meta tags will probably not help at all. It is unlikely to do any harm, of course, but they are generally not worth the effort.