I need to take a decision

It is important to you to clearly write down your decision (or problem) statement.

Ex: What car should I buy?

In order to decide properly, you need to state your objectives, i.e. criteria that you will apply to find the best option. 

Ex: for the car example, criteria would be, for instance:

- cost,

- performance,

- economy,

- insurance cost,

- etc

Identify the alternatives that you have.

Ex:

a) Ford Focus

b) Honda Civic

c) Audi A3

...(and so on)

Now it's time to evaluate your alternatives against all defined criteria. For this, use the following scale:

+++ Extremely Positive (Excellent)
++ Positive (Good)
+ Neutral (neither good or bad)
- Extremely Negative (Bad)

For the car example:

                               Audi A3                    Honda Civic               Ford Focus

Acquisition cost:         -                               ++                              +

Insurance cost:          +                               ++                              +

Economy:                  ++                            +++                             ++

total of plus:                3                               7                               4

In our case, Honda Civic would be selected.

Have you selected? It is time to register the selected alternative and why (i.e. the rationale) that option won.

In your example, your option is Honda Civic, because it received more "points" than the other ones. When there are more than one option (i.e a tie), maybe you will select the more balanced option, for instance. So it is important to write down the rationale.