Hey!!
Not so experienced but lemme tell you what I think.
A good pattern, in my opinion, would be one that integrates well into the map.
One that is easy to play, nice to look at, and one that represents the song well. The knowledge of where each object will go will come about with experience. Though it isn't just about where you place your objects but also about what your objects even are.
To explain these points in-depth I would need to explain to you how to map. There's other great sources out there that are more credible than I am so I'll refrain from doing that xd
And of course, don't worry about copying other mappers. Actually, I kind of encourage you to. When you copy a map's pattern verbatim you'll get an understanding of the pattern itself. Like why that circle was placed this far away from the other circle, or why the sliders are forming these crazy shapes, etc. You learn the logic behind placements and rhythm choices. Doing this would teach you about mapping in general.
If you need more information/tips, videos made by
A mo and
Pishifat are available to help get you going.
(Some things in Pishifat's videos may be out of date so beware)hatdog