Ask Experienced Devs

Good up front understanding of your problem space goes a long way. You don't need to waterfall it, but you should at the minimum have a high level view of the problem and your proposed solution(s). With considerations of where the team/domain might go wrong, where we expect to find pain points, and what sort of mitigations should be considered for those.

Your planning will not survive reality, and that's okay. You are already further ahead as a result of some high level consideration than you might otherwise be, and hopefully you have built your software under the assumption that you will be learning and changing as you go.

Human to human interaction is a baseline necessity for any large work for any field TBF. It's also hard failing point full of nuance, and doesn't really have a panacea as humans are the more complex parts of any system.

Software is hard, not treating it as such means devs will build complex systems because they focused too much on "simplicity". Missing the forest for the trees.