Hi Shravan,
You can have 12 CLs, 20 Earned Ls, or Privilege leaves and 10-12 medical leaves. Only EL can be encashed, for EL/ML, you can allow accumulation up to 60/90 days. For probationers, 1 CL per month. Maternity leave of 12 weeks shall be as per the labor laws.
In brief, while defining the policy, please ensure you mention leaves limit and accumulations, prefix/suffix with holidays, encashment details, general instructions like allowing/forwarding authority. Half-day leaves, supporting documents in case of medical leave extending beyond 5 days or more, leave without pay, special leaves if any. Study/professional leaves that are up to the management or can be adjusted from the existing leaves.
Further, just type leave rules in Google and you'll get more related info.
Thanks