At the start of my project I used the than available 20mm plastic figures for creating my wargame units. These were of Airfix and Esci. Later I added figures of HAT, Revell, Zvezda, Strelets and Italeri. To complete my minature forces I also bought a few 20mm metal ones, mostly from Art Miniaturen.
Building my armies, I did not only use the Napoleonic figures but also a lot of other periods, that with some minor conversions were turmed into suitable Napoleonics. In the late 80's I applied oil paints, switching over to acryllic painting no more than seven years ago. Some of my "old" units are shown.
It was Napoleon's Campains in Miniature that did it for me. This book contained good basic info, and advocated the use of 20mm plastics. Using a ratio of 1 figure representing 33 men, I made infantry battalions of 20 to 24 and cavalry regiments of 16 to 24 figures. Artillery batteries have 3 to 4 figs with 1 model gun or 6 to 8 figs with 2 model guns.
By no means I want to advocate the one miniature wargaming rulesystem above the other. I merely used this one and stuck to it, believing my troops can also take part in scenario's following other rules. I also wanted my mini's useful for taking part in games replaying other Napoleonic scenarios.