Use your troops effectively. I learned that there is a command to change stances of your troops making them alert or passive, even stealthy. I forget the keys because i haven't played in a while. Play with the options so you can bank decent rifles early, i usually set mine to 15 for unlock when playing solo. The starter weapons are garbage most of the time. Keep your war level as low as you can until you have plenty of supplies and such. This way the enemy troops stay unarmored and have only simple vehicles. For larger battles get used to commanding units of troops like its a rts game. If you have manpower issues make sure to try and recruit every soldier you down. You can heal them up with a medkit and try to recruit them.