Izzy that looks pretty good especially after your clean up work. You've gotten some good tips so far but just let me add my thoughts...
For starters the tubing your using looks a little large for 1/25. I stick with 1/16" when it comes to roll cages.
This is the process I use when soldering brass. By no means is this the only way, works for me so I stuck with. I use an $8 40 watt iron I found at my LHS. I prefer the iron to a torch because it allows me to get into tight spots with out loosening other joints. If you can get your hands on silver solder, get it. If not I use rosin core. Not as strong but still takes a major beating!
-Add flux to the joint being soldered, not too much or it gets messy. Melt the flux and heat the brass using a mini torch or a soldering iron. A small butane torch is handy.
-Add more flux a few seconds later but don't do anymore melting or heating
-Add a little bit of solder to the tip of your iron. The amount will really depend on the tubing size, but its much easier to add more solder then it is to remove it :wink:
-Apply the tip of the iron to the joint and allow the solder to flow for a few seconds. If you got plenty of flux on the joint, the solder should have welded it all up. If needed add a just a tad of flux and then add more solder.
If you did this right there should little to no clean up needed. These are just pics of one the frames I've done in the past... chances are you've seen them but just in case No clean up was needed.