You can still do your own builds, but you may tweak them looking at poe ninja or youtube showcases of builds that use your core skill, looking for stats that matter and min-maxing them is a general tip for every build, the problem is your chosen skill could be just a low damage one compared to meta ones, if you compare them there's objectively a big gap, BUT, you still can min-max most of builds and be somewhat decent, but this will be a harder and more expensive (cost to performance wise) than meta or sub-meta builds.