When ever you write an article about a topic about which you have previously written some other article its your duty to link to the old related article on the same topic so that reader can have access to the entire information about the topic in case he/she wants to read more, but finding related old article on same topic can be a really difficult through website or google search, a better way it to login in wordpress and go to posts section and then do a related keyword specific search for a topic.
Once you search it, you might find some list of article that might be related to the topic on which you are writing an article, for example if I m writing about an article on some youtube video downloader programs then I should link to some other youtube related tips and tricks about which I have written some old articles to which I should link to in this article, then I can search after logging to my wordpress blog dashboard and then go to posts section as shown in the image below, this is the wordpress internal search we talking about.
Now you will see all the posts which are about youtube tips or related, you can copy the link to the permalink for those article which you want to link. But now in the new wordpress version 3.1.3 there is much better easier way to link to old related posts when you are writing a new one which is related, you just need to select a text with which you want to hyperlink the old post and then press Alt+Shift+A and you will see the hyperlink pop up window as shown in the image below.
Now open the section which says or link to existing content as shown in the image above, and start typing related keyword which will get you all the old related articles as shown in the image below.
Once you find out the article you want to link to just click that article entry it will automatically linked to that word, and then click add link button as shown in the image below.
This way , the new wordpress 3.1.3 has made finding, deep linking the old article easy now. I must say this is really helpful feature for most of the bloggers out there.