I find this very useful when I started mapping and I still occasionally use it if I need too.
ALL MUST FOR ALL MAPPERS!
"Oh! It's my tail! It's my tail! It's a-twitch a-twitchin'!
And you know what that means!
The twitchin' means my Pinkie Sense is telling me that the control point gonna being captured by Red!" -
Pinkie Pie (quote modified for tf2maps.net)