I use Stay Brite, but get good results with 60/40 tin/lead solder. Starting to have problems getting good flux; the liquid Stay Brite might be the best for brass. You need good soldering equipment - a torch works, but for beginners a Weller 80 Watt electric iron is quite good. A torch can overheat things quickly.
The best flux I ever tried was Oatey's H2O - it was lead filled, and would clean even dirty brass. I haven't been able to find it in over a decade.