How to get more clients on FB?

I am doing marketing on FB. And lately it is not good on FB.
I am using FB ads to get clients for now but it cost a lot.
Any one can share some advice about getting more clients on FB.
I have tried lot of ways and used some tools.
I mainly use the comment function. What did you use?

If comments are your main lead path, the cost issue may be in the objective rather than reach: comment activity can be cheap without producing many real sales conversations. Run the same offer and creative in a Messages or Leads campaign alongside the comment-driven post, then track how many people become qualified conversations, not just how many comment. A Messages campaign is useful when you can qualify quickly in chat; a Leads campaign fits better when you need a form before follow-up. Compare cost per qualified conversation and the percentage that reach your next step. Which campaign objective are you currently using for the ads?