Its still not respect to go paint everwhere over signs etc.
I do pieces and such on big canvasses and have done murals as well as graffiti lettering of school names in my local area. Not all graffiti is destructive.
The best way to learn is to look at graffiti around your area and try too emulate that. DONT use/copy graffitigen.com
learn styles typical too your area as what you look at on there is generally a tacky style that would be considered "toy"
Just keep practising little pieces in your "black book" as it is called. Start with a pencil sketch. Then do fill, then color the outline, do shadows, keyline etc. its all pretty basic.
There are very distinct varieties f graffiti "taggin" is just scribbling on public property, however "piecing/murals" area respectful and decent looking form of graffiti that in most cases does look decent.
here are a couple of mine if your interested
i have also recently started on making stencils, mainly for custom imaging on my skate ramps but i am doing a massive a2 stencil for my son at the moment. they can be interesting if you do them right too
@Jansen i love banksys work, on all mediums he produces incredible artwork, a modern day srtistic genius, and he has made it in a way that no other artist has. graffiti, stencilling. as well as many others.