The Imagi-Nation gamer by definition, has a wider choice of uniforms in which to bedeck his armies of toy soldiers. There is also no right or wrong. You will not find the critic often found scrutinizing historical games who triumphantly announces that your facing colour is the wrong shade of puce, or that in that year the unit in question wore white, not sky blue and THAT shade of sky blue is far too light.......
Instead it is more a question of choice.....
The two extremes are to simply use whatever you wish or to emulate historical practice. The former can involve colour combinations rarely or never seen in the real world, the latter armies which are little more than copies of real ones (perhaps with more latitude in facing colours or a mix of units from different armies). Each has a pedigree among Imagi-Nations.
The reality is that sadly, there are only so many colours and colour combinations that it's unlikely your choice has not been made before you. I'd urge the neophyte to embrace this and not be afraid to mix and match and steal ideas wherever you find them! When it comes to the colours, your choice is really whether you stick with what was possible with the dyes then available, or simply indulge your imagination and be damned! Colours like a true purple were expensive and difficult to produce, but remember they are just toy soldiers and your toys at that.......if you cannot indulge yourself in an Imagi-Nation, then when can you?
When it came to making choices for my Soldier King armies, I had two defining themes; the first was a dominant colour from the boardgame; the second a desire to avoid historical clones as much as possible. Before I even started I gave this some thought and scribbled down some ideas and drew crude uniform sketches. My earliest such piece of paper has the basic line infantry uniforms for Bravance, Arcadia and Estavia....
In the game, blue with a white fleur-de-lis. This conjured a French influenced German state such as Bavaria, with hints of Burgundy and Brabant. I was drawn to Funken's Lace Wars and pictures of Prussian Freikorps, hence the "double blue" uniforms. Artillery were copies of Bavarian uniform. Other units had blue somewhere, with white and red as dominant colours. The flag was an early design with something very like Quebec and white with a light blue cross and large central fleur-de-lis in white for west and east Bravance respectively. At the point of completion, the cross became incised with a "V" at each end to make it more "germanic".
Yellow with a black lion. Dutch and especially Danish influences. Discovering (thanks to Neil Cogswell) that the Wurtemburg army of 1752 was uniformed in yellow clinched the choice of colours, influenced greatly by the Neuchatel Swiss of the Napoleonic period and Danish early C18th to include red and white. Playing the game had resulted in an experimental army of Guard cavalry and veteran line infantry. It was a natural progression to reversing the colours for the guard units. Some Prussian influences ( "black" hussars and jagers) included the flag design. The predominantly black and white was to tone down the otherwise bright colours.
Imperial themes naturally suggested Austria coupled with the greater range of facings seen in the Saxon army and it was white uniforms with the "rainbow" approach to facing colours. I ended up with groups: red, crimson, pink and orange; dark, mid and light green and yellow; light, mid and dark blue and purple. Cavalry were Saxon/Prussian cuirassiers in buff and crimson with red and green chevauxleger. Somehow white and light buff faced yellow have crept in there. The guards foot and horse are combinations or red, crimson and purple. Early Spanish wearing purple faced red may have influenced me, as well as references to "The Crimson Throne" of Estavia.
Hrvatska (obviously derived from Croatia) are red with a white eagle and carry hints of Poland (the eagle is very Polish). This meant red uniforms but I wanted something that wasn't British. During the C18th Poland belonged mostly to Saxony ( the elector was also king of Poland). Early Saxon uniforms were red......add in Hanovarians with buff small clothes and multi-coloured facings (there are some colours which work best with red). White and red were other themes or brown and red for militia and pandours. In the game lots of light cavalry are useful due to location, so lancers finishef the army. Artillery, Saxon clones (guns are in the main heraldic colour so red here) in green faced red.
Green with black eagle. Gave me more trouble than Hrvatska. I wanted to avoid a Russian clone, so green and red were the obvious combination to avoid. I struggled to find influences. The Kingdom of Italy became one, merged with Russian and Charles Grant's VFS to produce a three regiment guard in light green faced red with white small clothes. An early doodle had produced a guard cavalry in white faced turquoise. The rest were copies of other Imagi-Nation units: double green and dark green faced yellow. The artillery were the first diversion from real uniforms, white faced light green. Flags were influenced by Austro-Hungarian (green, white and yellow).
Hrvatska and Argozia have so far been the ones to present me with the most challenges. Even the smaller states have not been as difficult as it has just been a case of choosing one or two colours. Most are in blue with white, pink, orange or yellow as a secondary colour. There is one in black (based on a Prussian Freikorps), one in pink and another with hints of Saxe's Legion.