You can go out and get lots of irrelevant back links to your site, however this will not help you very much. You need to get back links to your website, from websites that have similar content and preferably from a page that has a high Page Rank.

You need to get links to your website from websites that are trusted and do not spam or have duplicate content. You need to check if the website has content that is of good quality and is relevant to your site. You should check what type of out-going links the page your link will be on has and ensure that these are of a good quality.

Different types of websites have different types of traffic. You don’t want visitors that are just visiting your site for a second and then leaving. You need quality visitors to your website who are looking for the type of content that your website offers.

You should look for sites that have the do follow attribute because these are the ones that will benefit you the most. Make the most of alt tags if you are placing an image advert or if its a text advert include keywords that are relevant to your website in the anchor text.

I will try and write some posts about link building and provide some places that you can use to create good back links.

1. Add your websites URL to website directories. This can take time, however there are directory lists online that you can download and go through submitting your website to. Once your have submitted your website a few times your browser will remember what you want entering in most fields which will save typing.
2. Add your website URL to your e-mail signature. This will encourage anyone that you e-mail to visit your website. 
3. Try E-mailing friends and family telling them about your website.
4. Add your website URL to forum signatures. Posting regularly will increase your signature links exposure, however do not spam just to benefit from this.
5. Submit your website to social bookmarking sites such as Digg, del.icio.us and Reddit.
6. Manually submit your website to Internet search engines.
7. Submit articles to article directories on a topics that you know well, including a link to your website.
8. Exchange links with other websites that have similar content to yours.
9. Use social networking websites to create an online network. You can then post bulletins about your site. The more people that are interested in your profile, the more likely they are to bookmark your website.
10. Use Internet groups to submit your website. Find ones that relate to your websites content on Google or Yahoo Groups.
11. Comment on blogs leaving a link to your website.

To make it more sucessful, find a niche for your directory to allow only certain links realted to that topic.

You can use PHP Link Directory script V2 for free to start one.

Follow this link and click phpLD2 at the side to download it.