At the begining of the game build up enought troops for 3 bases (hiearchy)

reapers: 4-5
glyph carver: 8
walkers: 2
monolith: 1-2

and 1 hero for each base. when you have enough troops, send 2 of the reapers, 3 glyph carvers and one walker as an escort, a few tanks would be good as well. move to an area far away from your starting base and build a new one there, then go back to the starting base and move your second groop of troops to another location (leave enough for starting base) position the new bases at the far edges of the map, this should create a large triangle in which you can ambush the enemy from 3 sides. dont forget to build up another army and additional resources for your other bases.