Hello, I'm gonna tell you about 5 must-have plugins/tools that you just NEED IT,

Essentials - Gives you alot of commands including kick,mute,jail,me,tp even smite
Multiverse-Core and Multiverse-Portals - Makes ability of making new worlds and portals.
AuthMe (CRACKED ONLY) - To password protect your account in server that is cracked.
CoreProtect - Most useful grief checking/rollbacking plugin/tool ever!
Vault - Core for 55% of plugins.