I suggest running x-com with openxcom installed.It improves the UI and fixes any bugs no matter what version you are playing.
Become an arms dealer! selling weapons is a great way to in income. Start when you can produce laser rifles.
At the beginning of the game sack any soldiers with low stats and replace them.
Rename your soldiers and include info about their strengths for an easy reminder. Example ..Bob Smith sniper. Mary Jane grenadier. Nick Jones scout.
If a building or wall is in your way just blow it up! Walking around every obstacle will get you killed and make the battles take forever.
If your having trouble finding that last alien or two on the map keep hitting end turn. Eventually they will get impatient and come after you. Set up an ambush!
Watch the geoscape closely. If you keep track of where alien supply ships are landing there is probably an alien base there. Instead of attacking right away focus on shooting down the ufos in transit for a good source of supplies.
If flying is easier than in Red Baron Im looking forward to trying out this game. I always found Red Baron to be very hard, but Im not an Ace pilot by any means. When I play rb I rarely even get to see the enemy before im shot down!
I played this game in the early 2000s and really liked it but couldnt get the sound to work for some reason. I replayed it recently and got the full experience. This is indeed a cool game. I completely forgot about it and im happy the DGC inspired me to play it again.