Economy
As has already been mentioned, credits are your main key to success in Mech Wars. Try to always have a steady income, and always build reserves for whatever reason you might have. Tough times will come, and you never know when. Having enough credits to survive is crucial, as you never know what might happen.
Katai Extractors can be killed or stolen, and hence it is very important that you check to see if your KEs are operating at full speed at all times. If you lose a KE (either killed or stolen), you must train a new reaper as soon as possible to prevent stagnation in the income stream.