hi shravan,
You can have 12 C.ls, 20 Earned.Ls or Privilege leaves and 10-12 medical leaves.
Only E.L can be encashed, for /E.L/M.L you can allow accumulation upto 60/90 days.
For probationer 1 C.L per month. maternity leave of 12 weeks shall be as per the labour 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 's upto the management or can be adjusted from the existing leaves.
Further just type leave rules in goggle and you 'll get more related info.
thanks