I have a chapter test tomorrow
Only one chapter.

The chapter is on: Congruent Triangles
Book: McDougal Littell GEOMETRY
Larson Boswell Stiff
Chapter 4

My grade in Geometry is rapidly decreasing, I have a B-

4-1 - Triangles & Angles
4-2 - Congruence & Triangles
4-3 - Proving Triangles are Congruent: SSS and SAS
4-4 - Proving Triangles are Congruent: ASA and AAS
4-5 - Using Congruent Triangles
4-6 - Isosceles, Equilateral and Right Triangles
4-7 - Triangles and Coordinate Proof

I am having trouble with PROOFS, all proofs because I don't know where to start because you have to find it out unlike algebra, and I am unable to :(
How do I remember these things, and when to use it?

Problems like these give me a hard time:
Plan for Proof -> Use the SSS Congruence Postulate to show that
Triangle PRQ is congruent to Triangle PRS
ANSWER: Because the corresponding parts of congruent triangles are congruent, you can conclude that angle PRQ is congruent to angle PRS.
These angles form a linear pair, so PR is perpendicular to QS

Sorry no pics. :(

Do you think anyone could give me tips on what to study?
Links would also work, even for other subjects, thank you.