all legal papers are clear like noc on land ,flat is not in any kind of controvesy, total area shown on papers etc should be checked. plus google it and check everything.
You should check every doccument and is that true one or fake. Is the person who is selling you is right guy or not and did any one already purchased or not
First of all you have to Find weather the papers of the Plot is a true or it a fake One you also see that Weather a Different People Does not Purchase It earlier.