CRM is a strategy, a way of thinking and acting. It's not a IT-Solution and no computer program.
It is fundamentally to have a personal and individual relationship with your costumers. Respect the behavior and preferences of your costumers and consider them with your actions.
In former times companyies liked to categorise their costumers like A, B und C. But from an actual point of view this attempt is short sighted and doesn't respect your costumers as they are.  E.g. not all A-class clients like to see the CEO every month - others do.
Your profit: cost reduction on avoiding inefficient approaches, reduces printing costs  less claims, direct, individual communication via the preffered channels. This leads to better more stable sales results and long term relationships with your costumers.

Noticed? No word about investment, IT-Solutions or even a computer program. Change your thinking and your perspective of view on your costumers. With this approach only you start reducing costs and increasing revenue of you money spent.