In my experience, the most common thing is to have trouble writing, since it's hard, specially if you're doing something worth it. After finishing writing a chapter, it's a good idea to wait a day or two before correcting it, eliminating unnecessary stuff and adding more if needed. Against the writer's block the answer is to write what you can, it doesn't matter if you delete it afterwards because you didn't liked it. Also, if you want to write to have to read many different novels.