Don't build the business plan from scratch - use an existing model. 12 SaaS financial models compared.
The business of SaaS: Understand why SaaS businesses work and how to grow them.
Good to know beforehand: "if you love writing code, you’re going to hate running a SaaS business. Instead of coding, the vast majority of your time is going to be spent marketing, selling, optimizing funnels, and providing support. Those are the things that get (and keep) customers. Those are the things that you do when you run a business. Not writing code." (from: Guide to Bootstrapping a SaaS Startup From Scratch)
Know what you're getting into, so you can have proper expectations: How to negotiate the Long, Slow, SaaS Ramp of Death - by Gail Goodman
The Startup Playbook, by Y Combinator's Sam Altman
The Startup Class from Y Combinator
Here's how I grew my app from $0 to $4500+/month in one year.
Building a repeatable, scalable growth process — part of David Skok's "Zero to 100" course on how to go from $0 to $100M
Do you need a co-founder? Answered by Arvid Kahl, who bootstrapped his business with his partner to $55,000/mo MRR before selling the business
The stairstep approach to bootstrapping — by Drip.com and TinySeed's Rob Walling
Market comes first, marketing second, aesthetic third, and functionality a distant fourth — by Drip.com and TinySeed's Rob Walling