Another convention I have used for the past ten years is to name each campaign folder starting with the year then the title, or part of it, of the campaign. You must use underscore and no spaces but my campaigns are all arranged chronologically so that even in the same folder, it is impossible to get mixed up:
I must admit I really hate to get some awkwardly named campaign folder that plonks itself randomly in the list. I usually end up re-naming everything I download to fit this system. Note, you can use the folder name to fine-tune its position in the order. I wanted BLITZ to follow SCOUT chronologically through the beginning of 1917 towards the year end. Therefore I used THE_BLITZ to move it down a space.
Done properly this allows you to shove everything into missions/campaign/(nation subfolder) and forget about it until you browse from the campaign screen. Its really interesting to go to the Campaign start screen and select different nationalities. From there you can quickly 'mousewheel' through the selections. In date order of course. No confusion, permanently organised and available.
This is also why it is important for Campaign Designers to make a proper INTRO file, with DATES and a TITLE and a bit of historical background plus any recommended settings. I also like the title screens in a similar format, so that I can browse each one easily and get a good scenario description, with dates...
Here is part of my RFC/RAF folder for example:
GB/
1916_AIRCO
1916_SOMME
1917_BLOODY
1917_SCOUT
1917_THE_BLITZ
1917_WAR
1917_WAR2
1917_WHEELS
1918_ARTILLERY
1918_PALESTINE
1918_PALESTINE2
1918_RECKONING
1940_BATTLE
1940_DUEL
1940_SCRAMBLE
1940_SIEGE
1942_DESERT
1944_MONTE
1982_CORPORATE
1999_SERBIA