Not bad advice, but I think numbering units into groups is a better option, and quicker too. Here's what I normally use (most of these carry over from the shortcuts I used to use in AOE, but unfortunately there isn't a group 0 in AOM, so if I have ships I have to compromise a bit):
1 - All military early, or infantry/cavalry/MUs later on
2 - Heroes
3 - Woodies (I use woodies to build as Egypt too) or Ships if it's a water map (Ships in AOE)
4 - Ranged military and ranged MUs
5 - Farmers early, Seige later on
6 - Military Buildings
7 - Spare, usually Roc or Titan
8 - Goldies
9 - Hunters early, farmers later (when all foodies are farmers)
0 - (Woodies in AOE)
[This message has been edited by DragonQ (edited 07-20-2007 @ 12:53 PM).]