Hi,
I will be starting a new LOA army in 10mm in a few months and have taken inspiration from this thread :
http://www.pendrakenforum.co.uk/index.p ... 622.0.html
If you are new to the period, perhaps look at a couple of Orders of Battle for inspiration. Even if you don't follow them exactly, it at least allows you to get a feel for the proportion of Infantry / Cavalry / Artillery and how the formations were organised at a higher level. I tried this approach when starting Swedish and Russian armies in 6mm a few years ago and found it very useful.
I'm not an expert on the LOA period by any means but understand that, to obtain the correct period feel, it is important to maintain the right proportion of infantry to cavalry (rough 2 infantry units to 1 of cavalry).
I would also heartily recommend getting the 'Beneath the Lily Banners' rulebook. As well as photographic inspiration, I am intending to use these rules with my 10mm armies.
As far as sources go, there is a huge amount of info on this very site. You will also find forum members very helpful and knowledgeable when it comes to guidance.
Cheers,
Phil