Yeah, I'm curious what you meant by solder paste MrDeb, cause true 'solder paste' is absurdly expensive has a short shelf life and requires refrigeration. It's meant to hot air reflow SMD components and is never used to prep a soldering iron for soldering. I bought a container of tinner/cleaner from radio shack which works incredibly well, it's a solid substance you dip the iron into which contains a solid mixture of acid flux and 60/40 solder, hard as a rock, you however HAVE to clean the tip off with a damp sponge before you solder with it to remove the acid flux.
I use the tinner/cleaner on all important joints, most stuff I just do a quick cleaning of the tip on a damp sponge, apply a little solder to tin it, tap it on a damp sponge again wait a few seconds and then go to soldering. Cleanliness is incredibly important in soldering in fact aside from temperature and the metals used for soldering it's the most important. I never let my iron sit at temperature for more than 30 seconds, that's why having a good ceramic heating element and a light tip is important, fast heat times short soldering times and a clean iron and it'll last forever.