For almost any activity, a large number of planning is always essential and same is true for software Testing. Without proper plan there's always high risk of getting distracted during the testing. If this specific risk becomes a fact, the results could be horrible.

Following are the 5 main parts of a good Test Plan:
a. Scope
 i. Overview of AUT
 ii. Features (or areas) to be tested
 iii. Exclusions (features or areas not to be tested) with reason
 iv. Dependencies (of testing activities on each other, if any)

 b. Objectives: This section describes the targets of testing activity e. g. validation of bug fixes, new features added or revamp of AUT etc.

c. Focus: This section describes what aspect of application will be included in the testing e. g. security, functionality, usability, reliability, performance or efficiency etc.

d. Approach: This section talks about what testing methodology will be adopted for which areas of AUT. For example, in the STP of an ERP application; the Approach section may perhaps contain the knowledge that black box testing will be approach for payroll. On the other hand, for reports the approach will be grey box testing.

e. Schedule: This sections describes that who will be accomplishing what and where on the AUT, when and how. Schedule section is, in fact, a ’4Ws and H’ of the STP. Normally it is a very simple table, but every organization may have its own customized format according to their own needs. Once the Test Plan is ready and application is under development; testers design and document the test cases. In the “Application Testing - Methodologies” section above, I have listed the TC design techniques.