A personal zine is a zine whose focus is on the author's life. As could be imagined, this leaves quite a bit of room for interpretation, depending on the lifestyle and\or writing abilities of the author. Production quality also varies a lot.
The typical personal zine has things in common, however. It is usually produced with photocopying, and stapled together by hand. It usually has a print run of between a dozen and two hundred copies. With such a small print run, of course, and the fact that zines are not a big monetary item, most zine writers do not hope to make a profit or even to recoup their costs. Most personal zines are either traded through the mail with other zine writers, or are sold at independent record stores for a nominal cost (usually under a dollar). If you are lucky enough to live in Portland. OR, you can buy them at Reading Frenzy.
The technical details of what makes a personal zine done, I could describe the typical artistic merits of one, and I could do it in a rather uncharitable manner. There is a certain stereotype, even within the zine geek community, that personal zines are an excuse for people to vent their feelings. And while I have read a great many personal zines that are of the "I am an alienated teenager" or "my boyfriend just broke up with me" variety, I have also read plenty that were funny, insightful, and showed a great deal of skill of someone turning their lives events into meaningful writing.