My main problem is that I wasn't cleaning the tip properly. I bought a tip cleaner/tinner and used it for the first time tonight. It's awful stuff, but it works. The solder flowed better, but my tape is still a bit bumpy. It just won't stick!
I made another memory glass pendant- a naughty flapper (image from the Graphics Fairy):
This just needed a little extra sparkle, so I put a few rhinestones on the corners, and added a copper crown.