The easiest and least time consuming option is to 301 redirect the old domain to your existing site. This tactic obviously works best if both sites are in the same sector and are targeting the same keywords; otherwise, if you have a pet supply site and you buy an old Texas Hold 'Em poker site, a redirect probably might raise some eyebrows among the search engines. If, however, your site is and you buy and 301 redirect the domain over, you're inheriting a lot of topical and appropriate links.

Nice one mate, another very useful tip to make your process water-tight would be to check the whois registration history. At times people recreate a replica of the old site using Using the tool, you can check when the original registrar’s time ended and if someone took over the domain before you. Great stuff John.
From a most basic perspective, any website or platform on the internet that allows people to post a link which goes to an outside site is a potential source of traffic. However, traffic sources are not created equal. Some traffic sources are very problematic. For example, if you were to go to social media sites and just share content and links, chances are, somebody at some time will object to that practice. They would say you’re spamming. It's very easy to get your affiliate account shut down because people complain. Similarly, you could be blogging for what seems like forever and fail to get much love from search engines.
Sometimes people purchase domains that they plan to build a website on or sell in the future, but it just doesn’t end up happening. If an individual decides that it is no longer worth the yearly investment of keeping the domain in their account, they may choose to let it expire. Or, someone might just forget to renew the domain before the expiration date. If this happens, it’s a great chance for other domain investors to score rare domain names that are pending delete. Spending time perusing the list of recently dropped domains can be a worthwhile way to find high quality domains.
It will just go on and on and on endlessly, so that really is like a set and forget setting. Okay, now before I show you it in action, I'll just skim over some of these stats stuff. Here this is pretty self-explanatory really so that's the amount pages crawled so far, that's how many pages were crawling per minute, so once it's been running for a minute that that'll date and they'll update every minute after that. That is if the websites are blocking are crawl. Thatw how many websites currently are been crawled, so how many websites have been crawled. That's if we have it have it had any registrar errors, so we fired off some domains to see if they're available or not and there's been any errors in checking them it displays there.
2) prerelease auctions.  These are domains where the auction venue has contracted with the registrar, like Fabulous or Moniker, to auction off non-renewed domains.  Just before a domain enters the pending delete process, it goes to a private auction to any person who has backordered the name.  Some people feel that back links on these type of auctions still provide a SEO benifit. My testing indicates that there is zero SEO benifit when these domains are redirected into another site.  So if you get a domain with "pink squirels" in a lot of achor text to a domain and then point it at your domain, you don't rank for "pink squirels"

Thousands of domain names expire every day. The reasons are different. Some owners forgot to renew the domains, some just don't want them anymore or they moved on to other projects. For most people these so called Expired Domains don't have any value. They just see a bunch of Domain Names someone else deleted and move on, but for the people who know about SEO or the value of good Backlinks, Expired Domain Names are money just waiting to get picked up from the street. The only problem is to separate the good ones from the bad ones. That is where comes into play.