How do you track sales & implement a process in a service-based business?

We're trying to establish a repeatable process within our service based organization by using a CRM and codifying the steps our sales & customer success reps take. We've looked at a bunch of different CRM packages and it seems like most are designed for either sales or customer success but not both. One of our "requirements" is to have integration with our telephony provider (RingCentral) which has also been surprisingly difficult. We're probably making this too complicated but I'd be interested to hear about how others deal with the sales & customer success divisions. Do you use separate systems and the CRM feeds something like a Trello or Asana? As the business scales we've had issues in the past with keeping up with everything but we also want more visibility into sales (mostly revenue projections).

To further complicate things when a deal is sold/won we have an estimated value but won't know the true value until possibly months later. The best fix I've seen is adjusting the estimated deal value to its true value once we know what it is. That might have to work but we'd also like to get better at the estimating part so want to track the estimate / actual value over time so we can close the gap.

It might be a mistake but I've intentionally not included the specific CRMs we've looked at and more details about our specific business. The idea being that I don't want to "poison the well". I'm hoping to get an idea of how others have introduced process into their service-based business (where the product needs to be kept up with and fulfilled well after it's sold).