The trend of closing polling places, allocating insufficient equipment, and failing to test equipment in "certain areas" has been growing every election cycle. Long lines do NOT mean high turnout. In urban areas, the opposite is often the case, as a high number of people see the line and turn around and go back to work or to manage other obligations.
Seeing lines in early voting is a VERY bad sign.
For whatever reason, Dems, particularly young Dems, tend to wait until election day.
Time is money, and lines are the new poll tax.
This is a form of disenfranchisement that needs to be at the TOP of the list of tactics that must be ended.
When long lines are coupled with overconfidence in the outcome, it's the perfect storm. This is what did in Hillary. The more confident a person is that their candidate is going to win "anyway," the more likely that are to go home when confronted with a line.
Beware overconfidence in Biden's lead. Between disqualification of mail in ballots and lines to vote in populous areas, shaving off 5% of Biden votes is not out of reach.
And when it comes to mail in ballots, we have to do more than encourage votes to get their votes in. We must emphasize the importance of reading ALL directions extremely carefully and double checking that all parts of the ballot are filled out correctly. They will be looking for the smallest error to disqualify these ballots.
As for what to do?
At this point, the only recourse I can see is taking jurisdictions whose plans allocate insufficient resources to manage high turnout to court.
In the long term, the ideal solution would be Federal law that imposes substantial fines for poorly run, unfair elections (creating barriers to voting or having a vote counted). Monetary incentive may not do it, but making it cost more to conduct an election badly than to conduct it well could help.