Regular matchup help defense with a spicing.

Put your best defender (D1) on point guard (P1). P1 is given a side.
Important - don't allow P1 to get within the grey area (within this area the guard has more passing opportunities).

D2 denies P2, as well as D4 denies P4.

D5 fronts off P5.

Weak side (D3) sags towards the middle line, yet within the passing lane.

Guard.

D1 prevents P1 from dribbling to weak side.

D2 plays a high deny. The only way the pass should go to P2 is by the lob (in that case D2 has a good chance of stealing the ball, otherwise D2 has time enough to get a good stance).
With the high deny D2 sends a mental signal to P1 not to penetrate towards the basket, because   of the risk of being doubled and lose the ball.

Strong Wing.

If the ball is passed to P2, D2 steers P2 towards the baseline! (Important to give P2 the "dead zone".)

D1 denies P1.

D4 denies P4.

D5 plays on the back of P5.

D3 sags towards the middle/ball. If P2 tries to lob pass P1 in the grey zone/weak side D3 steals the ball.

Low Post.

If P2 passes P5 on the low post, all players act as in regular man-man help defense. (By my meaning that is) D3 sags to middle line, D4/D1 sags to ball. D2 sags to ball and tries to steel if, and only if, P5 bounces the ball.

Many lob passes can be taken from a sleeping P2!

High post.

If ball is passed to high post (P4) D4 steers P4 to strong side. This to prevent the ball from moving to the weak side.
D1/2 sags towards the ball, yet standing in passing line.

D5 fronts of P5.

D1 denies P1 (this is normally the easiest pass from high post), to prevent the guard from getting the ball within grey area.

Weak wing.

If Weak side forward (P3), gets ball D3 steers P3 towards the baseline (closing elbow cut).

D1/2/5 sags towards the ball.

D4 denies P4.

Penetration.

If P3 penetrates towards the basket, D5 doubles right outside the paint.

D4 sags down, as well as D1.

Most important is D2. D2's job is to sag down and steel the baseline pass to P5.