Kargil was a fatal mistake at the decision making level. As the PAF officer who wrote about it pointed out - too many yes-men, no one to question fantastic and unrealistic plans.
So the plot goes "we will send in the military pretending to be militants and take a giant and strategic portion of Kashmir, cutting of Siachin supply lines. Then India will come to the negotiating table".
That's literally how childish and stupid the plan was.
It was obvious India would come at you with everything. In this case with 40,000 soldiers. And what did the PA do? Back out, run away, abandon its soldiers in the front lines.
If it was up to me - I'd say Pakistan should have planned for a full scale conventional war, as you plan for the worst case scenario not rosy pictures painted by your yes-men.
This means the following steps should have been taken:
1. Get everyone on board from the PAF to the politicians, to the foreign office to media.
2. Spend serious money upgrading and improving the armed services particularly PAF, leading up to the war.
3. After the initial infiltration success, push in regular PA units in large numbers to hold the ground.
4. Prepare for an all out war across all sectors and along the full length of the country.
Once Kargil was fully secure and Siachin was starved to death, and 2 weeks of kicking and punching on a full scale war was done with, both sides would be exhausted. After that, sue for peace based on the new realities on the ground.
Never take half measures and fight like a coward. Either don't fight or go all guns blazing. There is no passive-aggressive form of warfare that is successful outside the bedroom.