Choosing which style guide to use depends on your needs. If you need to cite a wide variety of sources and material types you probably need a very detailed guide. In this case the official manual for the style is your best bet.
NOTE: Most citation styles require that you cite the same or similar elements for each material type, but differ on things like the order and layout in which the elements appear. So, while the details may be different, the basic pieces of information you'll need to cite will often be the same.
Style guides will help you navigate these differences.
Some style guides are used extremely frequently. These links will take you to the UBC Library holdings on these major style guides.
If you've never used a style guide before it can be confusing to navigate. The index may be the easiest way to get to the page you need to consult, but first you need to analyze your source and determine which citation elements you'll need to record.
Step 1: Start with authorship
Step 2: Look at the type of your source
Finding the rules for citing different types of sources works the same way as finding out how to cite different types of authors - consult the index.
Step 3: Look up the formatting rules
Make sure that you look up the rules for formatting your citation both in the text of your paper and in the list of works cited/bibliography.
source: http://wiki.ubc.ca/Library:How_to_Cite/Using_Style_Guides