A tricorne, stock torso with lapels & crossbelts, add a musket or sword and call it a day. My approach is different. And a lot more time consuming, I must admit. In fact, the prep work takes darned near as long as the paint job. The figures start with these materials:
To my eyes, a stock Lego minifig comes up lacking in 18th Century style. The bulky coats and cuffs of the early 1700's are more the look that I wanted. The cones are used to create the cuffs. Drilled these out with a Dremel tool and bisected. The Indiana Jones messenger pouch when cut down works quite nicely for the cartridge box. Waist belt front and back is styrene. From the waist down the coat is made of cardstock.
The stock Lego musket is toylike but scales out better than the more realistic BrickWarriors or BrickArms replicas. Also, the curve of the stock allows it be grasped by a minifig's inflexible hands. Added a bayonet, cut the sword length down and re-attached to the hilt. There you have it.
And several as completed, above and below.
Having run short of the messenger pouches, I used the downtime to create an officer. Lego has a lot of women's hair accessories, this curly one makes a serviceable periwig. For the rank & file, I used ponytail parts combined with green stuff.
Coming soon, flats !