Colon Use or Not

It depends on you. For example, when I'm filling the timesheet I used to write it down as below:

I have worked on below tasks today:
-task 1 
-task 2

And some people write it as

I have worked on these tasks 
-task 1
-task 2 

But what I feel and prefer is to add the colon is the correct way to follow. Because in books they follow colon to show what character is saying, like

James: hi
Jhon: hello 

How we read it?

James says hi, Jhon says hello.