I use a few plugins and presets that help me map faster and better with JOSM. I recommend them as basics for people who are starting to map, or even experienced mappers if they find them useful.

Plugins

• FlatLaf: Dark theme for JOSM across all platforms. This isn’t needed but it makes JOSM way easier on the eyes.
• Gridify: Generate grids using an area. Very useful for generating parking spaces quickly.
• OpeningHoursEditor: Visual editor for opening hours
• utilsplugin2: Adds various tools to JOSM I find useful, personally circle arc is my favorite because it lets you create smoother curves and turns on roads, sidewalks, and the such.
• easypresets: Create more specific presets of existing presets for faster editing.
• buildingstools: Draw rectangles quickly. Combine this with Advanced mode on and Create Areas (built into JOSM when Advanced is on) can make adding buildings really, really fast!

Tag Presets

I only use one tag preset called Name Suggestion Index. This allows you to mark businesses with their proper name, wikimedia tag, amenity, etc. This is the same index that iD uses for its suggestions, so this will give you very similar tag presets that iD does. I find this very useful for people moving from iD.