Extra gear is easier to paint separate, attach with CA glue or Elmer's white (wood glue) neither will effect the paint. Heavy items in soldiers hands is a different challenge. Many figures have open hands to accept weapons ect. Unfortunately they appear to not have a tight enough grip to give the illusion of weight. Shepard Paine liked to use clenched fists or hands molded all ready holding something, the weapon was cut apart to fit both sides of the hand using this method.
Best to get the fit right before paint and then decide if its feasible to paint the weapon separate.
* super cool looking 'blued' guns:
Paint flat black, dry brush gun metal (silver darkened with black) Use enamel paints for this step. Next mix a wash using Tamiya acrylic clear 'smoke' + clear blue. don't over do the blue for military arms. Wash metal areas of the gun. After its dry paint the wood parts with enamel paints.
As for figure's skin tones concentrate on getting the color right, shadows + highlights can be added using washes + dry brushing. Fine detail like eyes brows can be 'drawn' on after the figure is over sprayed with flat clear with pencil crayons. DO NOT use 'flesh' paint without mixing red &/or brown in it. NEVER use yellow in skin pigments. (jaundice)
In this mix you can see both shadows + highlight colors. When painting multiple figures try and vary the figures as to not look assemble line painted*
Hope a tip or two helps, good luck & post some pics!