Played some as Axis on Red October, paying special attention to the camuflage. The Axis uniforms are extremely hard to see whenever they have any kind of buildings or shadow behind them (which is most often the case when playing around buildings/ruins). They stand out more if just in the open. The Allies were definitely not badly camuflaged if having brighter things behind them (moonlit structures, snow) and I did not get any impression that they were 'glowing' in the snow.
On spartanovka, the Allied tan uniforms camuflage well, better than the Axis. Especially with anything wood, dirt or sand coloured behind them.
As Allies, do everything you can to try to make yourself small, don't move around so much. Try to break the outline of your siluette by paying attention to what is behind you (that the enemy will see from their perspective). If possible, always pop out to the side of an object instead of above it. On maps like Grain Elevator, there is a big difference in how hard you are to see in some windows compared to others. I've personally been able to spend 5-10 minutes in a row machine gunning Axis with a DP-28 some floors up from a window. Consistently.
As Axis, stick to buildings, shadows, rubble. Pay attention to which windows the enemy can 'see through' the building and avoid those - your siluette will stand out clearly against the sky or any other bright surfaces. Also, shoot less; being dark in shadowy areas, the muzzle flash is much more apparent than from an Allied soldier firing from a well lit area.