SEO 101 is not difficult... and works really well in non competitive areas. When a keyword(s) is competitive, thats when it gets tougher and you need more than the basics..
As I have said before, basically, hypothetically and conceptually:
ranking = importance x relevance +/- quality signals
Importance
Search engines try to rank the more important sites first:
*importance is largely based on link popularity (Google calls it PR) - the more links, especially from higher PR sites, the better --> seen as more important a site --> rank higher
* links from authority/expert sites (ie Hilltop theory) may also be an 'importance' factor
*lots of good content is needed to get the links
Relevance
Search engines try to rank the most relevant sites higher. To be more relevant to a particular keyword(s) you need:
* Keyword(s) in the title, description, H1 tag and have the highest density on the page, but still keep low as possible and flow natural with the text (all the other placements of keywords count for so little I do not worry about them now)
* Keywords in the anchor text of incoming links - this is currently the most important relevance factor
* links from other sites on the same theme/topic (ie TopicSensitive Page Rank theory)
Quality signals
Search engine try to rank the better quality sites first, so look for "signals":
eg
* do nothing that gives any hints that you are participating in link exchanges for the purposes of ranking better (ie link for the benefit of the user)
* don't link to a viagra or casino sites unless you are a viagra or casino site
* do not lin to link exchange sites
* duplicate content issues
* etc