There are hundreds of way you can optimize and promote your website, but there is a lesser amount of methods that don't go against any human ethics or search engine guidelines. Why would you want to stick to ethical website optimization?
Lasting value, long-term results
When you use ethical (white hat) site optimization and promotion methods, you go along with the search engine guidelines. This means they won't drop you from their index and you'll keep getting a steady stream of visitors.
More real customers
When you work for your customers, you put your ads where your target audience is. You also build business relationships with the real people to offer a quality article for publication, etc. Thus, you know who arrives at your site and what they expect on your site as well. Untargeted methods (like spam) can't offer such effectiveness.
Less work, more results
When you are focused on providing value, you get high return on investment, because you only engage in activities that you know will drive noticeable continuous results. Thus, you can build a set of practices you use to optimize and promote your site, and stick to them, this way saving time for not using short-term methods.
When you work with the real people (including site webmasters, bloggers, editors, etc), you build a reputation of an expert in your field. Publishing quality information in industry journals, participating in forums and blogs, you provide value to your potential customers and build a positive reputation as well. This will make it easier for you to acquire customers, because they'll know who they are going to work with.
Get word of mouth
When you focus on providing value to your target audience, your customers will begin to respect your efforts as well as what they get from you. Coupled with established reputation and trust, your site visitors will be more likely to spread the word about you and your site and link to your site in the way, too. They'll also refer some customers to you directly, too.
Work with the colleagues
When you focus on building quality content and giving to your customers, you also build relationships with your peers on forums, blogs, etc. This allows you to network with the right people, who will be able to help you some, if you need it, mention your content on their sites or refer customers they can't handle.
Easier to get published
When you are known to provide quality to your customers, building relationships with your peers and have overall trusted reputation in your field, as well as for being an expert, it will be easier for you to get published in industry journals. Which can drive you customers, links, more respect, easier to get published, etc.
When using ethical optimization and promotion methods, you should focus on your customers. By doing so, you use the right keywords, place them right, create quality content and offer your quality content for publication in respected magazines, thus building relationships with your potential customers.