Ask HN: What product management ideas and resources do you find useful?

Hey all, we have been building products for a long time. I'd describe the process as agile-ish, arriving it after realizing that we are always overbuilding in some areas and underbuilding in some. I say agile-ish because we do not stick rigidly with all its tenets. The context that is probably important is this is a small team where the product manager is reasonably technical and has intuitive understanding of feature difficulty and the team is fairly small. People who are/have been in similar situations, what helped move things faster, reduce slippage and blindspots. Thanks!