When you have built a large enough army for a successful attack, make sure to use the team hot keys that are described in the manual for the best efficiency when in a dog fight. Once all the units in the attack force have been highlighted, start to move each team at a time to various points among the map. Keep in mind that some units are much faster than others, so make the different points relatively close together -- make sure that the faster units wait for the slower ones. If they do not it would defeat the purpose of bringing all the units in a team. Even if you make teams with the same units, being able to click from one group to another during battle is far better than to keep highlighting each group of units when you want to control them. Once in battle you can rotate from one group of units to another and focus their attack on focal points in either the opponent's army or base structure (bigger heavily defended units and structures such as a construction yard, heavy factory and repair facility, etc.) This strategy results in faster more effective attacks with less of your units lost.