This is completely off the top of my head.
Objective quick wins:
1) Less code. The less there is the less there is to debug and maintain. This applies to all code including dependencies, frameworks, abstractions, and decoration in your own code. If abandoning OOP means substantially less code then do it without question.
2) Iterate faster. If you have a build that takes 10 minutes and the next guy has a build that takes less than a minute they can fail 10x more frequently and achieve the same level of productivity.
3) Know your foundations with confidence. Things you rely upon become more of a barrier than a help given a long enough time line (shorter time line that could otherwise imagine).
4) The point of software is automation. If you find you are doing manual curation in the code you are likely wasting your productivity. An investment in better automation returns interest on the initial investment.
More opinionated personal preferences:
1) Unless you are writing in a language where you manage access to memory, such as C++ or Rust, abandon OOP. In garbage collected languages like Java, JavaScript, C# it only provides composition. It is a tremendous increase in code that does more harm in troubleshooting.
2) Prefer a statically typed language. As a JavaScript developer I have fallen in love with TypeScript. There are performance benefits to ensuring all primitives are strongly typed, but the developer performance benefits come from typing complex types. This is a quick win for defining execution of microservices and functional programming.
3) Prefer functional programming techniques and code portability. Code is less defective when it is highly predictable and explicit.
4) Save composition for last. Don't worry about how to put things together. Complete each micro-task in isolation, which forces a separation of concerns. Once everything is written putting things together becomes natural and typically works itself out.
5) Avoid pronouns in the code. The pronoun of JavaScript is the keyword this. Don't use it. You don't need it. I have been writing in this language full time for 13 years both at work and for personal projects. In that time I have really needed this only twice. The problem with pronouns is that they aren't clear (in either value or intention) by just reading the code, which takes substantially more time to interpret as a human.
6) Think in writing. You can save some refactoring effort by having a solid execution plan. The best way to plan is write things down as if to explain it to somebody who has no idea. If you cannot even explain it to yourself you won't be able to do in code.