Sculpt the LoA first

 It starts with the LoA (line of attack). You have to decide which LoA you want to use. Then you sculpt it. And then you put your attacker on it. 

Don't start with putting your attacker on the LoA! In doing that, you show your hand, and give your opponent the chance to oppose your idea.

White to move

If, for some reason, you decide that invading with your rook to c7 is the LoA you want to work on, you can act in two ways.

If you place your rook on 1.Rc1, you show your hand, and give your opponent the chance to block your idea by 1. ... b5

After 1.Rc1 b5

In fact, you might have simple wasted a tempo.

Pawns are the slow moving sculptors of the LoAs. Look at the difference:

After 1.c4

Dependent on how your opponent reacts, you can decide whether you place your rook on c1 or not.