if you a beginner artist or still learning  , I think you might face that  drawing from imagination problems , if you try to invent a character or location or specific action you try to look for it on your mind but nothing comes out!!!

So you go to a reference and start to copy from it and make your touch... is that right??? Or should the artist draw from his mind directly?? And how the beginner can improve that and built a library in there mind!!!!

Well naturally you can only get better from practise, and expirence, so if your having trouble imagining things just draw from what you know, what you have seen, and what you want things to be like, (trace styles you like from looking at them) and then over time it will become easier.