[ilikejam]

These...

https://reflectivesupplies.co.uk/products/salzmann-3m-scotch...

are better than plastic plate reflectors in every way.

[epakai]

Somewhere I picked up the idea to place reflective tape on the inside of the rim between the spoke holes. Not really for side visibility, but for front/rear off-angle visibility I like it. You can alternate (say every 3) to produce a flashier pattern when you're moving.