Boss Order
In the Mega Man games, you gain new weapons with special abilities by defeating the bosses at the end of each level. Part of the strategy for beating the game is figuring out which order to play the levels to ensure you have gained the most effective weapon to face each boss. One effective order is starting with Bomb Man using your own default weapon, then proceeding through Guts Man, Cut Man, Elec Man, Ice Man, and Fire Man using the previously gained weapon on each subsequent boss. Although Guts Man doesn't give you a fireable weapon, you use his super arm to defeat Cut Man by throwing blocks at him.
Repeat-Hit Glitch
"Mega Man" has a glitch that you can exploit to your advantage when using the rolling cutters from Cut Man or Elec Man's thunder beam weapon. When you fire either weapon at an enemy, hit the "select" button the moment the enemy is struck. This will cause the game to pause, and each time you hit the select button thereafter, the game will register a new hit to the enemy, even though you've only fired a single shot.
Beating Dr. Wily
The final challenge in beating the game will be facing your arch nemesis, Dr. Wily, who created all of Mega Man's other enemies. In the first phase of taking on Dr. Wily, the doctor faces you in a large machine. Use the fire storm weapon you gained from Fire Man as an effective tool against the machine. Once you've disabled the machine, use Elec Man's thunder beam to hit Dr. Wily and then hit the select button to use the repeat-hit glitch.
Unlimited Capsules
Throughout the game, various locations have energy capsules to recharge your health or weapons. After using the capsule, continue onward to scroll the screen past the capsule's location. When you return to the same location, you should find a new capsule in the same spot. Repeat the energy-capsule process until you are fully recharged.