The required contents
Every matrimonial petition follows a settled structure, and each part does a job.
The mistakes we most often have to fix
Pleading conclusions instead of facts. "The respondent treated the petitioner with cruelty" is a conclusion. What the court needs is what happened, when, and where.
Omitting reliefs. Custody, maintenance and return of stridhan claimed as afterthoughts are much harder to run than reliefs claimed in the petition itself.
Overstating. Allegations that cannot be proved damage credibility on the allegations that can. Family court judges are experienced at spotting the padded petition.
Getting jurisdiction wrong. A petition filed in the wrong court can be returned, costing months.
The joint petition is a different document
A mutual consent petition is signed by both parties and states that they have been living separately for the required period, that they have not been able to live together, and that they have mutually agreed the marriage should be dissolved.
Its most important part is the settlement: alimony, custody and visitation, property, and the withdrawal of other proceedings. That schedule should be specific enough to be enforced without argument, because a vague settlement clause is one of the very few things that brings a consent divorce back to court.