SC - strategy of solving.

Many of the problems are "deductive" in nature and use strict logic.
In these the conclusion MUST be true.

You must understand a few simple rules of logic such as:

If P then Q is true
Given P then Q.
or given NOT Q then NOT P.

Also, you must be able to translate English into logic.

Q only if P
if P then Q
All P is Q

some tricky ones are:

P unless Q (equal to if not Q then P)
P is necessary for Q
P is required for Q

Simple diagramming techinques are very helpful here.

A decent GMAT prep book should steer you in the right direction.

The other type in Inductive reasoning. In this type, you form your conclusion based on the strength of favorable evidence.

You must learn to recognize how various premises support and undermine your premise.

HTH,