A friend of mine who solder rollbar for rally cars teached me something and the cause of the "roughly" aspect of the soldering is just because it's cold; if you warm up the component, and then you put some stain on it, you just have to put the wire, and touch the stain, that will flow on the wire.
If you are fast and the stain stay hot the solder point will become shiny and smooth, even without the fluxe

That is how my friend explained to me, but i always do that, and the results are very good