Every business is driven by its business model. It should provide very clear structure on your profit influencers. In general in every model you should be able to identify your revenue components (quantity and price) and cost components. Having disassembled your profit into the key components you will be able to derive many common financial ratios. As you are in SaaS B2B segement, you should closely monitor:
1) lifetime value of your customers
2) associated cost of customer acquisition
3) add, churn and net movement of your customer base
4) cost recovery time (how many months of revenue it takes to offset the cost)

And quite a few more depending on your business goals and strategy. Would be happy to hop on a call to explain more.