How to Proceed with Deindexed Domains?

I would either:
Fix the issues and then use a new domain or
Fix the issues and request re-inclusion

I would not just fix the issues and redirect a deindexed domain to the new domain.

Thank you for the information. If I fix the issues and then use a new domain without redirecting the old domain, I wonder if it will think the new domain is all duplicate content (from the old domain)?

It all depends if you ask me. Is the domain so good that it is worth keeping or is it easily replaceable by another domain. Is it getting a lot of traffic from other sources, that would make you want to keep said domain name?

If the name is not that great and not getting traffic on its own I would just dump it and start over with a new one and not repeat the same mistakes.

If the name is a really good one that you want to stick with, I would fix it and then request reinclusion to the search index. Just be warned it could take a good while.

Terrific, thank you very much for the information. I am going to try using a new domain name. I got into trouble by having multiple sites as separate subdomains of one domain name. So my plan is to merge any subdomains from a given domain name into a single site and place that on a new domain, and just abandon the old domains without redirecting. I have no particular allegiance to the old domain names.

I just renewed all these domains too, so now I lose out on about 10 months of domain use by abandoning them. Thanks for the info. Indirectly I think that is what happened. Some of the subdomains on a given domain had what I would guess they considered 'substantially similar' content. It wasn't spun but many of the topics overlapped.

I don't know why I did it that way to begin with, I guess it was just easier and cheaper than getting separate domain names. It's live and learn I guess. Fortunately I had a number of sites with no subdomains, those are all still indexed so far, even where they shared the same ip with ones that did get deindexed, so hopefully those will be in the clear.

There's a number of improvements I've been working on to the sites, the next is getting far better navigation, because that is very lacking. Also have far too many internal links on the same keywords so I have to fix that I think too. These things all take time of course and there are only so many hours in the day.....

Get a new domain.

It worked! Thank you all so much. I could see G crawling the new domain, but it took about 3 days for it to appear in the results.