There are numerous books on the market to help you research clothing and accouterments for the period you wish to portray. Whether you want your costume to be good enough or your garb to be as historically accurate is possible, books about the subject are a good place to begin. Amazon is a great place to pick up books. I'm including ads for some of the ones that I've found.
Renaissance and pirate clothing is extant and sometimes used to derive patterns. The authenticity of those garments, and the patterns that are created from them, is a subject of great debate.
This book on swords was recently reviewed at Omnivoracious in a post titled "A Mind Swimming with Swords: An Interview with Swords artist and author Ben Boos"