If you like characters that have fireballs and uppercuts then Jago is your character in Killer Instinct. His Endokuken fireball is done by quarter-circle-forward any punch. The light version goes the slowest across the screen, while the heavy version travels the fastest. Use this to keep your opponent away and to make it difficult for them to get closer. On block, Endokuken builds a ton of meter which can be really useful at higher level play.
A good way to follow up an Endokuken is with Jago's Wind Kick, performed by quarter-circle back and any kick. This gap closer is also a combo starter with the light version traveling the least distance and the heavy version going the furthest. When following an Endokuken it is very difficult to avoid. As an added bonus it also jumps over low attacks!
If your enemy is jumping over your Endokukens to get close to you, you have Jago's classic uppercut, the Tiger Fury to anti-air them. This is performed by forward, down, down-forward and any punch. Imagine you're making a Z shape with the controller. The Tiger Fury uppercuts have invincibility on startup, so Jago cannot be hit by anything when the move begins.
His last special attack, the Laser Sword, performed by quarter-circle-back and any punch, is useful to apply pressure up close. The medium and heavy versions have the advantage on block, meaning you can act before your opponent after they block it. This advantage is minimal, but it is enough to go into his Medium Punch back into Wind Kick as a frametrap.
If the opponent is sitting back blocking your Laser Sword, then it is time to use Jago's 50/50 mixup. He has low crouching medium kick and his Back Heavy Punch Neck Cutter for an overhead. Either of these can be cancelled into a Wind Kick to combo, so your opponent had better block correctly!
Besides crouching medium kick, Jago's best normal attacks are his standing Heavy Punch and standing Medium Punch. Both have more range than you would expect, and can be cancelled into Wind Kick or Laser Sword to combo. If jumping at your opponent, you'll want to use jumping Medium Kick and Jumping Heavy Punch.
When it comes to combos, Jago's specific combo mechanic is called Around the World. After hitting an opener, Jago can combo with only auto-doubles as long as they are decreasing in strength. The one exception being that after a Light attack you return to Heavy. For example, you can open a combo with Wind Kick then follow it with Heavy Punch, Medium Kick, Light Punch, back to Heavy Kick, then end the combo with Tiger Fury. Lastly, Jago's Instinct allows him to regain life and recover faster after attacks. Use it frequently to give yourself more possible life than your opponent!