There are various rules to remember for how to conjugate mandates. Doing so will make it much easier.

Mandatos Formales: Presente Subjuntivo

Salir → Salga
Poner → Ponga

Prohibiciones Formales: No + Presente Subjuntivo
Mandatos Informales: Imperativo

Tú (él en presente O irregular)
Irregular

There are various irregular words, and these are important to know. 

Tener→Ten
Venir→Ven
Decir→Di
Ser→Sé
Poner→Pon
Hacer→Haz
Salir→Sal
Ir→Ve (Also ver, but that's the regular él form)

Vosotros (infinitive r → d, no irregulars)

Salir -> Salid
Bailar -> Bailad

Prohibiciones Informales: No + Presente Subjuntivo

Positive: Haz!
Negative: No hagas!

Positive: Haced!
Negative: No hagáis!