There's far too many things I'd have to mention to teach someone how to play, but let me just mention the basics...
1. Change your controls to Blocking with LB/RB, this will make substitution MUCH easier. 2. Learn to dodge your enemy's attacks by jumping (press A only once, ninja-movement is too dangerous, even if it's fast) over them. 3. Don't bother with melee-combos, almost all of them are easy to punish (substitution -> ultimate). Learn your favorite character's fastest attacks (quickest possible start-up and lowest possible vulnerability time after the attack) and focus on using them, if you can. 4. Ultimates and Team-Attacks are much harder to substitute...especially the latter. Don't risk it, block them if you can. 5. The ideal team is Balance+Offense. Balance will protect you from an ultimate, offense will strike the enemy back at you whenever he gets knocked away (and the enemy is completely vulnerable to your attacks during this, if he can't substitute them).
Dos and Don'ts....I guess you mean what to do to prevent people from hating you? >_> -don't just stand there. If you do nothing except wait and sub+ultimate, people will consider you boring. -in the same way, don't just keep guarding and blockhop non-stop. Same as before, fighting people like that is boring. -New players seem to hate "spammers" (in this case, n00b-talk for someone who brainlessly uses jutsus over and over again non-stop). -You can't substitute while you're doing something (i.e. if you're currently using a jutsu or combo, you won't be able to sub until it's over). -air combos are much safer than most other attacks. -usually, people dislike Awakenings (especially Itachi's Susano'o), as they tend to be ridiculously overpowered. In the same way, people tend to dislike those who completely depend on the Team-Attack (pierces through anything, extremely fast and instant activation time, deals ridiculously high damage...~50% health)
It takes great courage to become a NEET! Having the guts to admit that he only wants to eat and sleep all day...isn't that what a real man should be like!?