There are a lot of things to keep in mind that would make this answer REALLY long. But, one of the most important is simply to remember your audience. As educators, we tend to get caught up in scholarly jargon and forget the simplicity that we need to reach our audience sometimes. Also, be specific to which level of audience you are targeting. Elementary? Secondary? Higher Ed?
And lastly, don't overanalyze. Create a plan, then GO! Course correct on the way!
You cannot please everyone (be ok with firing some customers). This will affect what and how you develop your product. Additionally, keep it simple and make it easy for teachers to get started, deciding in advance your monetization strategy. Nothing will cause a greater outcry than putting previously free tools behind a paywall because you decided one day it was time to make money.
Bonus: research funding opportunities on schools' behalf so they have an easy way to pay for your product. Are there grants available that your product would qualify under? Could Title 1 funds pay for your product? Etc
By way of background, I built the first website to be ever licensed by a ministry of education in *1996* and subsequently served as a VC associate for a five hundred million dollar fund focused almost exclusively on education investments.
Below, I've listed the most important factors in no particular order.
Money: Regardless of your product, you will need a team that investors are willing to bet big early money on. An ideal first raise is between two to four million dollars. You will need this because you need much longer runway and much more investment in sales efforts than almost any other type of web or mobile-based start-up before it's likely you will have meaningful revenue.
Distribution: How do you acquire new users? Do you require permission from an administrator to be deployed? A teacher? Both of these are challenging. If your product isn't relying heavily on students forcing adoption of the educators and/or administrators, your Company could die an early death, even with ample funding.
Team: Connected very much to the first two points, you must have a team capable of inspiring investor and educator confidence. It is easier to inspire investors than it is to educators. It takes a very special type of sales-person, one who is actually a great listener, shows genuine compassion for the customer, and ideally, has some credibility (if not personally, then behind them in the rest of the team) in the problem you're attempting to solve. Who is doing the selling matters most, and ultimately, if the CEO is ineffective at this role, they are likely not long for the CEO role during the startup phase at least.
Speed: Everything moves more slowly in this sector. It will take you at least twice as long as you reasonably forecast it will take to achieve your plan.
VC expectations: Read up about the "Series A" crunch taking it's toll on many teams and add extra crunch to education-related enterprises. The proof points are even higher and harder to hit in education, than they are in enterprise or consumer.
If you're not altogether discouraged and you think you have what it takes, or can assemble what it takes to win here, I'd be happy to do a call with you to discuss the particularities of your startup.
Best of luck!
I won't address the factors common to all digital startups here, and focus on factors that might be specific to education, and B2B in particular.
* Understanding the Sales Cycle - it's different in education, particularly K12 and HE (at least here in the U.S. market). It's important to plan revenue and projections, accordingly. The time to move through the entire sales cycle can be longer than anticipated (if you haven't had exposure to K12, for example).
* Understanding the Audience - who is it for? and who are the stakeholders? Like most B2B plays, you are likely going to interact with multiple audience types / personas - define them and be intentional with your approach towards each (whether it's via sales, customer development, implementation support, etc)
* Articulating Value - there are many ways to define value in education. Some of these are clearly financial in nature, but many, many are not. If you're building something aimed to increase levels of student achievement, teacher efficacy, etc, then think about to position your product / service in the right way.
Hope this helps and is somewhat on track.