I give the same advice that I would give to athletes.you know, technique first, speed second.
If there are words that you don't know you should look them up.
If there are expressions that you don't know, you should try to understand what they are .
When we work in a second language we never work as quickly as in our first language.
We're used to reading quickly knowing what we need to know and doing something with that information.
So I think it's important for students when you're studying the language.
I think it's important to take your time, look up your words figure out the grammar ,next time you read that same passage you're going to understand and that's when you'll build speed.
Just don't get discouraged stick with it , It's slow at first but it's only slow at first and you'll never become fast if you don't take those slow steps first.