I can tell you about procedure in maharashtra.
1. Buy about 1 acre of non-cultivated (barren) land. This is permissible to a non-agriculturist.
2. Cultivate some grain food. For example, rice or juar. Or at least, plant some fruit trees.
3. Inform talathi, circle officer. They will perform panchnama with photos of the grown crop.
4. Prepare report and forward to tehsildar for his comment/approval and recommendation to appropriate authority who will allot 7/12 abstracts which is a certificate itself as "farmer".