+ The green space stations can be destroyed either by shooting all 6 pods, or by landing a single hit to the center opening. The pods are 200 points each, and destroying a station is I believe 1500 points. So if you shoot all 6 pods you get (6 x 200) + 1500 = 2700 points, vs. only 1500 if you go for the quick kill. Obviously, going pod-by-pod is more dangerous, so there is a risk/reward tradeoff.
+ A good beginner strategy is to go pod-by-pod for the first 2-3 stages when the game is still at "starter" difficulty so you can rack up some points, then focus on simply surviving in the levels after that. In later levels you have to work quickly to clear the level to avoid the dreaded "condition red"
+ shooting the spikey mines and space rocks gets you so few points it is not worth your time for that purpose. However, when you're coming up on a green station, sometimes it's worthwhile to clear some of that stuff out to give yourself some space to maneuver
+ It's easy to fall into the habit of focusing on a single green station, destroying it, and then moving on to the next one. That's fine when the stations are spaced far apart. When they're bunched together, a better strategy is to shoot at all stations on the screen to take out all pods that are in shooting range. Remember, the stations use the pods to fire at you, so clearing out as many as possible means fewer bullets to dodge.
+ You might have the tendency to always shoot up/down/left/right, which is fine for many situations, but you really need to learn to take advantage of shooting on the diagonal to take out pods and enemy ships from a wider range of angles. This seems like it should be obvious but there really is a tendency to stick to the cardinal directions, especially with some joystick styles that favor those directions.
+ Always look at your radar to plan your route so that you waste as little time as possible just flying around (remember, "condition red" happens to slow pokes). Sometimes, the quickest route to the next station is to "wrap around" the screen Asteroids style (i.e., fly off the left side of the radar to appear on the right, fly off the top to appear at the bottom, etc.) This can save you a lot of time.
+ When you hear the game say "battle stations" and the squads of ships attack you in a formation, there is always one ship that is a different color than the rest. If you take out that ship, the formation will break up and retreat, which can save your life. You do get a nice bonus for killing all of the ships in a formation, though, so it's something to try if you have a clear shot.
+ The little yellow ship that flies by and says "fighter sighted" is spying on you. If you let him get away (i.e., fly off-screen) then your threat level changes. For example, if you're at condition yellow and a spy spots you and lives to tell about it, you'll find yourself in condition red. So, it's often worth it to try to chase those guys down and take them out, even though they're only worth a measly 200 points.
+ yes, a pint is required