What's your opponent's character weakness?
Cloud's recovery, for example, is subpar and linear. Take advantage of this to win.
How does your opponent recover?
Your opponent recovers high or low, or if your opponent is Fox/Falco/Ike, he might recover by using forward specials.
How many jumps does your opponent have left?
Kirby and King Dedede have multiple jumps, but most characters only have two and one up special. Using up special for most characters isn't safe as an option for jumping. If your opponent has one jump, wait for that jump.
Does your opponent air-dodge a lot?
Wait for your opponent to air-dodge. Lure him to dodge if he's above you on-stage, or see how he responds off-stage.
Does your opponent roll a lot?
See how your opponent rolls and which direction he rolls often. Does he roll left, then right or right, then left, or both? Don't roll with him.
Do you try to spike your opponent off-stage?
If not, you should probably learn to do this. You can make it easier to win.
Are you chasing your opponent?
Some players use characters who require spacing and zoning. It might be difficult for you to win if you don't know how to deal with an opponent who is constantly running off. Learn to pick up another character who you find comfortable and enjoyable who can deal with these types of players.
Know how to set up combos with your main.
If you have a main who requires set-ups, it's best to learn when to use those set-ups. When your opponent lands, that is typically one way to set up a combo by first going for a grab. With a character like Zero Suit Samus, you'll want to use your neutral B and d-smash and properly space these. You'll also want to be sure that when you go for a grab, that you time it right so you don't run past your opponent and miss the grab.
Know how to combo.
Zero Suit Samus might be known for her ladder combo, but that's not all she is, and even if your opponent is anywhere between 30% to 50%, don't feel that this is all you can do. If you can ladder combo, do so. Practice it so it becomes second nature.
Use effective zoning tools.
If you main Zero Suit Samus, learn to z-air properly to space. If your opponent gets close, switch to n-airs or even b-airs. Be sure to short hop and fast fall. Make sure you're at a distance that allows you to avoid getting grabbed.
Look at your opponent's character.
If you're looking at your own character when playing, you're going to miss out on what your opponent is doing. You need to know what your opponent is doing. Look at your opponent's character.
Have fun.
Seriously. Have fun. If you're getting frustrated, that can affect how you play.
Accept loss.
Everyone loses. The important thing is to take your loss as a learning experience. When you lose, don't let it discourage you. Your opponent isn't learning anything by winning.
Save and watch replays.
Write down what you did correct and what you didn't do correct. This helps you keep in mind what you can do next time you're in a similar situation, or if you're even not in a similar situation. If you did a falling air-dodge and got punished for it, just make sure you don't do it again. A falling air-dodge is when you're falling and you air-dodge, obviously. This typically causes you to land onto the stage, which can mean a win or loss depending on how close you are to your opponent.
Play online and practice.
If it gets laggy, leave the person you played. If it continues to lag, it might be you. If you decide to practice against a computer, leave the computer at level 3. Don't fight level 9 computers. Their AI doesn't adapt to the degree that human brains do. What you want to do then is practice with your main. Don't worry about the computer fighting back. That's not what you're practicing. You're practicing so your brain processes and ingrains your new skills.
