There are a few commands that can be useful when playing on the server. Here are a few of them.
Spawn a big tree (Creative Only): /bigtree
Select walking / flying speed (Creative Only): /speed <1-10>
Change gamemode to Survival: /server survival
Change gamemode to Creative: /server creative
Each player can set their own homes where ever they are, to make it easy to get back to a place. To make it even better, each player can set up to 15 homes, so they can travel between multiple homes or places.
List of home commands ingame: /help home
List of homes (if you have multiple): /homes
Teleport to your home: /home (name of home)
Set your home to your current location: /sethome (name of home)
Remove a home: /delhome (name of home)
The 'back' command is used to get back to where you was before teleporting somewhere. This can be useful if you for example teleport to a friend, and want to get back to where you where prior to the teleportation. By using the 'back' command, you get teleported back to where you was.
Teleports you to your location prior to tp/spawn/warp: /back
To claim land on the server, stand in the middle of where you wish to claim your land and use the command /plot. All claimed plots can be seen in purple on the server map. Use this to see if your plot covers everything you wish to protect.
View all commands: /plot
Display plot boundary: /plot scan
Claim a plot: /plot claim
List your plots /plot list
List your friends' plots /plot flist
Teleport to plot /toplot [plotname]
Rename a plot: /plot rename [plotname]
Delete a plot: /plot free
Get plot details: /plot info
Add a player to plot: /plot trust [player]
Remove a player from plot: /plot untrust [player]
Increase plot size: /plot upgrade
Decrease plot size: /plot downgrade
Set plot center: /plot setcenter
Set plot spawn point: /plot setspawn