Hi

Heavily depends on you payback time for customer (how long in months it takes you to get money back invested in acquiring them). If it is more than 12 months than you have to work on reducing the cost of acquisition. Without lowering the cost (and lowering the payback time) the growth wthout funding will kill you - you will have exhausted all the money before getting to the payback time.

The other thing to do when you have long payback time is to work on increasing the value of customer. This is usually done by introducing annual payment (for SaaS solutions), up-selling, cross-selling and other (full list how to do it you will find here:https://medium.com/@asengyczew/19-best-ways-to-boost-your-ltv-the-ultimate-guide-61b9417fd779)

Now, if the payback time is short (6-12 months) than just try to exhaust the market - get 100% penetration, approach new potential customers, The bigger share you want to get the bigger range of acquiring customers you will have to use. Some people do not react to offers by mail or phone so you have to go old-school and have direct sales.

Sometimes, the niche is too small for your appetite (or too small to sustain the business in the long run). In those cases you have to find other customers – either go global or look for other similar segments / markets where you can use the same solutions.

Hope it helps

Best
Asen