Basic Strategies of Nonogram

You can adopt two basic strategies:

1) Consider the possible positions of a group, for example:



The possible positions of the group of 5 red squares can only be one of the following:



In all cases, the three squares in the middle must all be red, so you can be sure that those squares are red:




2) When one end of a group is known, the remaining squares of the group can also be known, for example:



Consider the green square. Since it must be the rightmost square of the green group, the position of all squares in that group can also be known:

I used the two basic strategies and mastered the entire game! How do you figure out the basic strategies?