Character of the owner is important. Some original owners are conmen. In shags - I buy basically based on character - because some people even if you sign - will give you problems.
Due diligence is not rushing to land ministry - someone could have been paid - to falsify information - and you're being led to kraal - go do land search etc.
Just assume the land has no title - like in middle of turkana or maasai - but everyone knows who owns what - through word of mouth.
If you want to buy land in area xyx - spend a week there - in bars - and markets - find out everything about the area from anyone. Conmen are well known. It unlikely you'll be first victim.
If you cannot - hire an investigator.
My would buy from original owner. Who he could verify hisptey of ownership. Usually his agemates. He would never deal with a third party. That is the way to do it. Due dilegence on top of it.