If the property is an REO/Bank Owned, I personally discard it.
For the remaining entries in your list, simply pull them up on your Appraisal District website as you have done. There should be a data field that contains the owners property address, city, state and zipcode. Here is an example of this information from Tarrant CAD.
If the owner address contains no information, then you will need to dig further and do a bit of research to obtain what you are looking for. Here are some things you might try:
1. Talk to neighbors, this is a fantastic way to gain additional information on a given subject property. They are often anxious to help you get in touch with the owner since that vacant property on the lot is an eye sore and dragging down property values.
2. Check public records. If you can locate a deed of trust on the property you can contact each of the grantors listed. See illustration below. Google these individuals and dig around to see what the information might yield.
3. Do google searches for the owners name if you have that information available. For instance, I was able to locate information on an owner via a PDF for a company the individual worked for containing contact numbers.
4. If all else fails, you could consider utilizing a skip trace service such as TLO.com or accurint
Once you have their information, reach and out touch them with a marketing piece or phone call.
I hope that was helpful, best of luck.