It's the little details for me that are an important part of the look. So personal items, those period pieces that you match to the uniform and time frame you are portraying.My interest is US Advisors to the ARVN units.
I have a couple watches, mainly Seiko, pictured is my Seiko 7005-8030 produced in 69 (black faced Seiko watches were purchased directly from the manufacturer in bulk by Ben Baker who was the department head of CISO (Counter Insurgency Support Office) and issued throughout the different SOG Supply Offices (S-4). Two variations of the watches were issued to cross border personnel to include a time date and non-time date) and a Rolex replica of a style plausible to be a PX purchase in Japan. I noticed in a number of photographs from the period the wearing of silver bracelets also.
The next item is eyewear, the BCG or Birth Control Glasses, if you wear glasses you can easily have prescription lens fitted, the ones pictured are period issue and marked with US nomenclature, as to sunglasses, I prefer the Randolph Engineering HGU4/P which have been produced since 1958.
Paracord, yep, paracord, vietnam paracord had a black fleck, so anything you need to tie up, use black fleck paracord, I always have my penknife and church key off my left belt loop.
Dogtags, everyone wore them but again they can be personalised, I have my P38 can opener and a small crucifix. Knowing where your can opener is all the time is a good thing. I also carry a period zippo. The square one on the left produced in 1937 where the engraved zippo is correct for the period. I bought whilst in Da nang back in 2012. It's authenticity unproved however very accurate.
For one of my Advisor looks for a pack, I have a tropical, a lightweight, a ciso but my preference is the Arvn. Flare tube, rope, rigger gloves (gloves are a must when holding hot C-rats). When choosing your load out think about what the purpose is and remember the key items, ammo and water!
Find a period picture you like, use it as a guide and you can't go wrong.