Using BibDesk should be pretty natural for the average user of BibTeX. Simply open your .bib file with BibDesk and start working. See section Managing References To get you up to speed faster, here are a few important features and differences from other BibTeX editors.
If you are used to writing LaTeX code for accented characters and special fonts, you will be glad to know that BibDesk handles most of that for you now. See Editing References for an overview, or Character Conversion for more detail.
If you use braces in your BibTeX fields to protect meaningful capitalization, BibDesk attempts not to interfere. The braces will be saved and any previews will show the intended capitalization.
Searches will match the string without the braces - a search for "LaTeX" will match a publication with the title "{L}a{T}e{X}".
If you have a BibTeX file that is not stored with ASCII encoding, BibDesk will work with the file's encoding. See encoding-notes and Character Encodings for further information.
BibDesk can help you maintain useful and readable citation keys painlessly. See Cite Key for more information.
BibDesk supports BibTeX macros. See Editing Fields with Macros and Editing a Document's Macro Definitions for more information on how to edit them.
BibDesk searches and sorts entries that utilize the BibTeX `crossref' field, and allows creating `crossref' entries easily. See Creating and Editing Crossrefs for information on adding `crossref' links, and Crossref for configuring `crossref' options.