The official boy scout uniform guide can be reviewed here.
Merit Badge Sash. If worn, merit badges are attached to front (and back, if needed) of sash. Venture/Varsity letter is attached at bottom front corner. Temporary insignia (camp patches, Totin’ Chip, etc. or additional merit badges) may be worn on back. It is worn from the top right shoulder to the left hip. The Sash may be attached underneath the Epaulets, or attached to the Epaulets with a special pin.
Order of the Arrow Sash. Only the Merit Badge Sash or the Order of the Arrow Sash may be worn at one time. The sash should be attached underneath the right epaulet, and draped to the left him. Neither one should be looped over the Scout belt at any time. The Order of the Arrow sash should only be worn to Order of the Arrow functions, or at times when the Order of the Arrow is assisting with a troop function (such as Order of the Arrow elections).
Shoulder Epaulets. Green shoulder loops identify Boy Scouting (all members of a troop).
Left Sleeve. Council patches, unit numeral, and badge of office are worn as shown snug up, and touching each other. Badge of office is centered below and touches unit numeral. If the Scout is trained for leadership position, they may wear the “Trained” patch below the badge of office. The veteran unit bar (25, 50, 55, 60, 65, 70, 75, or 80 years) is positioned above and touching troop numeral and in turn touching council patch. Den chief cord is worn over the left shoulder and under epaulet.
Left Pocket. Service stars above the pocket. If a medal or embroidered knot for youth members is worn, service stars are raised. Embroidered square knots are worn centered above the pocket in rows of three. Not more than five medals may be worn, pinned centered immediately above the pocket (extending over knots if both are worn). The wearing sequence for knots or medals is at the wearer’s discretion and lead color is to the wearer’s right. Badges of rank are worn centered on the pocket above the Arrow of Light Award. Flap buttoned. The World Crest is worn centered horizontally over the left pocket and vertically between the left shoulder seam and the top of the pocket. If the scout has a “ring” patch, these are worn, surrounding the world crest patch.
Right Sleeve. U.S. flag. Only the most recently earned Quality Unit Award may be worn below patrol emblem or below National Honor Patrol star. Musician badge, if in band or drum corps, is worn 1⁄2 inch below patrol emblem. Up to six merit badges may be worn on the long-sleeve shirt in two columns of three starting 3 inches above the bottom edge of the cuff.
Right Pocket. Jamboree insignia (only one) worn above BSA or interpreter strip. Order of the Arrow lodge insignia worn on pocket flap. Temporary insignia worn centered on the pocket. Flap buttoned. The interpreter strip (up to three) is worn above the BSA strip embroidery. A nameplate, if worn, is centered above the BSA strip and the interpreter strip.
The shirt is to be worn “tucked in” to the pants or shorts.
Historic and previously loved uniforms are acceptable with patches worn similarly to described above.