[a_tartaruga]

Reduce what you are trying to build as much as possible. Then reduce how much code you use to build it. Build something you can use as soon as you can. If you're writing a ton of code before this thing is getting used then how do you know that you actually need all that code?

[AnimalMuppet]

"What's the simplest thing that could possibly work?"

You may need clustered databases with failover. First you have to get enough users for it to matter. So don't start with that. Start with a simple, single database. Yeah, think about the future - pick a database where you can move it to clustered - but don't plan out every detail of how you're going to get there. You don't need it now, and you may never need it.