1) It’s a good idea to replace your techo in mission one with a moehog. It is very difficult to use all of your pieces together at once, and the techo is the least valuable of all your soldiers. The moehog you replace your techo with can move farther faster and hit more times. Two moehogs will always beat a moehog and a techo.
2) It’s also a good idea, if you can, to grab an extra set of healer grundo gear (store it on the extra moehog) as you approach mission five. You want to replace the extra moehog in mission five with a second healing grundo (assuming your first grundo has reached healing status). Once you have two healing grundos you are almost unbeatable, since not only do grundos make excellent healers, but they are usually among the strongest pieces you have both offensively and defensively (if equipped with a healing scroll and a grundo cloak).