How do artists create original drawings

Have prints made from drawings

SaWaHave prints made from drawings

Hello everybody,

I need prints of some of my pictures - some quite small (like a postcard format), some as large as possible.
Somehow I can't find a provider for something like that on the net. I land on pages where I do Art prints can buy from various artists or on pages where I can have flyers etc. printed.
I now have a few pictures via the photo service from Bipa as a greeting - or Postcards ordered, that looks at least better than the prints I received in a copy shop. But there was little choice when it came to paper ...

Does anyone know and can tell me a provider?

And one more thing: friends would like to have some of my drawings as posters. Now I have just found out that I can enlarge drawings in A4 format to a maximum of 30 by 30 format. (For pages like Posterjack - larger formats are not accepted at all because of poor image quality).
Now my drawing is not a photo and maybe you can't compare it at all? Would the quality really be that bad?
A I scan 4 drawings at home and I thought, this is how I get the best quality? Or should it be done somewhere where there are better scanners?
I actually have a good camera, but I can't photograph drawings because the white is lost.
So go to the photographer and have it done? Or where there are bigger scanners?

Sorry for the many questions!

best regards