Belt
Useful not only for holding up pants tightly to the waist, ensuring good weight distribution, but also enables attachments like pouches.
Buy a synthetic material belt, ideally one which can be used in professional circumstances, with very little metal (no big belt buckle), so that it need not be removed for airport security checks.
Cargo pants/ shorts
Can be found in military stores or online. Professional look is achievable.
If heavy items are carried in lower pockets, belt is required.
Carrying items in back pant pockets can slightly affect sitting posture.
Vests
Types and purchase spots
Tactical vests are not suitable. Ranger vests or (photo) journalists/ travel/ carry vests have many large pockets inside and outside (both in the front and in the back). Ranger vests tend to come with full zipper. Journalist vests tend to have larger and more pockets. Those made with mesh are the lightest.
If a suitable material (cotton or polyester + cotton or mesh) is used, the vest is light and breathable, therefore is fit for use in summer.
Neatness
Black colored ones tend to complement light colored shirts well, and are suitable for professional use.
Goodness of fit is variable. In good vests a draw chord is provided.
Can be used to hide crumpled shirt and loose fitting pants.
Use in Carrying/ storing
They distribute weight over the shoulders very well; thus they are very
comfortable.
One can store items in the vest while varying shirts and pants.
It is also convenient to place all carried contents together for inspection at airports.
Non-clothes Attachments
Bags.
Pouches
Often equipped with special detachable loops, so that the pouch can easily be attached to a belt. These are often marked Molle compatible pouches in Military stores, where they are often available for cheap.
Waist pouches
Maxpedition thermite versipack is conveniently part of a belt.
Leg drop pouches
The lower strap, if tied can cause chafing; so it is a good idea to leave it untied.