SEO - off site techniques

The off-site SEO is a bit of a minefield, but bear in mind that you can get position one without any offsite optimisation if your keywords are 'niche' enough...
Getting links is possible from one of four methods that I can think of, and be aware that there is a value in a link whether or not anybody ever sees it or clicks on it. Search Engine 'bots' will see the link regardless of whether it is seen by your potential visitor, the bot will also take note of what is called the 'anchor text' ie. the words that are highlighted, for instance I might use the words SEO genius to link to my blog that deals with website building, search engines et al... having anchor text with specific keywords is considered key to off-site optimisation.
These are the different links you might have:

• Directories: Getting yourself listed in directories is fairly easy, there is even software available to help to automate the process, still painstaking, because most directories allow a certain amount of automation ie. the software populates categories like 'description' 'keywords' 'URL' and 'Title' etc,,, for you - you still have to add them by hand - or pay someone to do it for you... Some directories make a charge, others are free - I prefer the free ones! - it may be a risky process as some sites are blacklisted by search engines and it may have a negative effect if you get yourself listed on one of the 'bad neighborhoods'. An indication of a 'good' site would be whether the site is 'cached' by Google or whether it has any 'PageRank' (the google toolbar will tell you this or a browser SEO plug-in such as the one I use on Google Chrome).
• Paid links: many people get a company to find websites that will insert links for money - blogs often carry 'sponsored posts' or 'reviews' from which they get a small one-off payment. Other will use networks and forums to offer sponsored links directly to site owners and bloggers - invariably, they will request a specific anchor text - in fact they will often have three links in each post which has to be a minimum length (100 words, 200 words etc.). Google do NOT like this, and will punish sites that they find are doing it - the cynical person might argue that is because Google like to be paid for their own 'sponsored links' in search results - I think ultimately the monopolies commission may take a dim view of the way that Google controls search results, and 'punishes' sites that try to 'compete' with paid search engine entries (a company can legitimately pay Google to appear in position 1, but will be 'slapped' for paying someone else to try and achieve the same result..)
• Link exchanges: I can't possibly keep track of how many times I am asked to place a link on a site in exchange for an external link back to my site. It is important to realise that Google recognises a link exchange, and treats them accordingly eg.. If you link to 'joes carpets' and joes carpets links back to you, the link won't be as effective as when joes carpets links to you and you do not link back ie. if you get 'one way' links to your site, your site grows in 'authority'. So most webmasters indulge in what is called three way linking where the link that comes back is from a different site. The danger is that the link you are offered in exchange is possibly valueless, and unless they are in the same niche as you, there is little point anyway. This is the dilema then, your competitors are in the same niche, but they're not going to link to you... Your suppliers may link to you, you may get colleagues or consultants to link to you, but you can spend a lot of time asking for links and will rarely get anyone take you up on it...
• Ghost sites: which brings us nicely onto the last point, if you can't get sites to link to you, make your own... create a site which to all intents and purposes has content that is liked to yours, has all the right keywords and is optimised... then start linking words into your site - ideally picking up on anchor text. don't forget that you are not really trying to drive 'traffic' to this site or even to your own site - it is ONLY the link that is important - as long as you can guarantee that the site is 'crawled' and 'cached' by google, then the bots should automatically attribute authority to wherever those links point - and these are 'one way' links, nothing comes back the other way. Of course you can take this further and make more ghost sites which link into this ghost site, thus bumping up the authority down the line...

That's about the long and short of it, you can use searches to find out what your competitors are doing, there are supposed 'formulas' for keyword density and all that, but I think content should be 'organic' and should flow naturally rather than be made to fit into a formula that may or may not have an impact. At then end of the day, Google is looking for cheats, so don't go looking for short-cuts. Build good sites with good content, everything else should stem from that starting point.