First of all, master the basic concepts and theorems thoroughly and master more classic examples. Substitution is also abstracted from concreteness. Secondly, do a certain amount of exercise. Consolidate the knowledge learned from exercises, and learn some problem-solving skills and ideas.

To give a few examples: In the section of learning cyclic groups, as long as we know and master two typical examples, one is integer plus group (z,+) and the other is residue class plus group of module n (Zn,+), because there are only two kinds of cyclic groups in essence (i.e. isomorphism), their properties can be copied (i.e. isomorphic mapping) to any cyclic group. When these two examples are studied clearly, the cyclic group will be clear.

Another example is the direct product of groups, which can be associated with the knowledge of direct sum decomposition of linear spaces, and the two are very similar.

Substitution has many connections with advanced algebra, elementary number theory and other mathematical disciplines. For example, the nature of the order of elements involves the divisibility of elementary number theory, and the theory of domain involves linear space and polynomial theory.