Answers by Expert:
My expertise is in US, but I have a lot of exposure to worldwide, and with wide reference material, I will do what I can to answer questions about global stamps. In US I have extensive experience in all aspects (does include Administrative overprints for Cuba, China, Puerto Rico etc.). Also, Hawaii general issue and Revenue (pre-statehood). Of course still building knowledge but have been collecting since 1980. Air Mail is a favorite area, but not a limitation. Two specialty areas are Large Banknote issues, and Washington/Franklin identification. Strong experience in Carrier & Locals, Private Die (Also known as M&M for "Match & Medicine" but also includes some playing card and perfume stamp issues.) Recently have been building more back-of-book experience, especially around Official, Newspaper, Revenue and tax editions. Some covers, and cancellations, but not my strong suit. Another area I'm recently diving into. What I can't do: Anything non-US, as it's just not an area I focus on.
30+ years of learning the hard way. A lot of passion for collecting and dealing (as I do both). I don't consider it a hobby... I consider it a serious pursuit that I'm able to do in the hours I'm not occupied by annoying things like sleep.
I work closely with some of the global leaders in the expertizing and identification field. Have co-authored several papers (with Mr. William Weiss Jr.) related to identification, as well as tool set to help with quickly identifying the more challenging areas of Washington Franklin. Strong experience in paper types and coil validation.
Member of APS #222356.
1870 - 1879 Large Banknote Issues - Easy Identification (co-authored with William Weiss Jr). Washington-Franklin - Easy Identification (co-authored with William Weiss Jr.) Detecting Fakes, Alterations and Counterfeits (APS Summer Session Expertizing Session materials with William Weiss Jr.)
Thousands and thousands of hours of pouring over hundreds of collections. 30+ years as a collector-to-dealer, avid student of philatelic study. Pre-1900 variation is fascinating, and it seems even after all these years, that I make some discovery every time I look at a new example. APS Summer Session - Fundamentals of Expertizing 2014
100's too numerous to mention.