You can mix and match your pieces of equipment any way that you want to. While it can be tempting to increase your damage power with every upgrade, that will still lead to you getting killed quickly because there are times when it’s unavoidable to take enemy fire. Increase your armor and your life to make sure that you can take a lot of hits before you finally get knocked out.
If your hit points get low, wait around for awhile and try to avoid enemy fire. Every five seconds or so, your ship will recover about 5% of its hit points, roughly. So if you are at 100 maximum health, you’ll recover 5 hit points every five seconds. Especially use this if you get into a tough spot with a boss yet can still manage to avoid their fire.
Bosses in general can only generally be beaten if you majorly slow down your gameplay. Focus on, as was said on page 1 of this guide, avoiding all enemy fire, even to the detriment of the speed of shooting down the boss. Avoid the boss’s fire, keep moving, and sweep back and forth, hitting the boss’s weak target spot as you pass by. Whenever you get the chance to do so, sit pat for a short time and hit them with some extra firepower.
To speed up boss battles, make sure that you catch an attack gem before you fight against the boss. Then when the enemy’s weak point opens and (when applicable) after you aim it, use it to do as much damage as possible. Try not to use an orange gem against a boss because it’s completely useless against big targets. Orange gems are most useful against groups of small targets.
Do all of the same strategies above when taking on the minibosses, except the battle will be easier due to a much bigger target (the whole ship) and generally due to less powerful shots. Of course, you’ll still have to deal with little ships flying all over the screen and bugging you, so don’t lose focus.
Remember the time trick? The one where you set the time ahead on your phone to regain all of your energy. You can do the same trick after you finish playing the secret missions in order to get them to pop right back up again. All that you have to do is set the time ahead by somewhere between 12 and 24 hours after you complete these missions.