You can also improve ways manually by dragging the nodes, adding nodes directly, dragging segment midpoints etc. You can use tools like https://josm.openstreetmap.de/wiki/Help/Action/Extrude and https://josm.openstreetmap.de/wiki/Help/Action/ImproveWayAccuracy .

If any of that seems confusing or unclear, please don't hesitate to ask in the Zulip chat, and we can also plan for some OSM event - maybe even a mapping party, closer to spring?

Making mistakes is perfectly fine, but it is crucial not to repeat the same mistakes a lot. Better to ask early :)

(if "mapping party" sounds confusing, that can also be discussed :) )