As a frequent traveler, I have a certain "uniform" and process for getting checked in and through security with the least hassles.
As far as what I wear, I avoid anything with clunky metal (i.e. belts, necklaces, bracelets). I have a PA, but do not wear it through security. I wear shoes that are "easy off / easy on". I have my laptop computer out, my liquids in the bag, my shoes off when I hit the front of the security line.
Even the order in which I put things on the x-ray is all designed to make my process quicker: Shoes and liquids first in one bin. Laptop computer in second bin. Briefcase/Laptop bag next. Carry on backpack last.
When I pass through the detector, I usually don't have any problems because I plan in advance not to wear anything that will cause me delay.
Once I'm through, I put the shoes on my feet (I tie the laces once I get out of the security screening area). Grab the liquids. Grab the laptop, which goes immediately into the briefcase. Then grab my carry on (backpack). I exit the security area and tie my shoes. I then take my belt out of my carry on and put that on.
For international travel, consider what may be on your laptop computer in regards to encryption products and any "entertainment" or controversial content. It may be illegal to leave the U.S. with certain "strong encryption" products, and it may be illegal to bring those same encryption products, or controversial content, into your destination country.
Know before you go.
Aloha and Be Well!