welcome to OSM, and thanks for your contributions.
A few things I noticed:
- You can square the corners of buildings by pressing "Q". If the building has curves or strange angles, you can draw all of the orthogonal parts of the building first, square it, then add the details.
- source tag should go on the changeset, not the objects. You might see a source tag on some objects from old imported objects, but in general putting them on changesets is sufficient.
- Adding tags like trolley_wire=no is not necessary, since they are assumed to not be there in the first place. 

Let me know if you have any other questions. Happy mapping!