i have not been following the midterms and do not have any suggestions. but, i again must point to the dominant factor in the previous cycle: if you are a poor person or a minority in a district held by the republicans at the state level, your ability to actually cast a ballot is, at this stage in history, actually quite precarious. it's gotten to the point where polling firms actually have to scale back their numbers to account for voter suppression tactics. and, what happened in 2016 is that they didn't scale it back far enough - even as i was arguing that they were manipulating data to absurd extremes. to properly account for the range of tactics that republicans are using to prevent people from voting nowadays, you need to perform surgery on the sample.
what that means is that the democrats are going to have to eat into the republican base if they want to actually win seats in these regions. it's not enough to work up minorities and poor people, because when they get to the polling places, they won't be allowed to vote. they have to make the ground up amongst demographic groups that are actually allowed to vote.
i don't know what the data says on this point because i haven't been following it. but, don't be surprised if you hear things like there was "low turnout amongst hispanics and african-americans".