Winner take all states distorts the strength of a candidate.
I would make one simple change that puts the primary on a par with the national election:
Every congressional district would have 1 delegate and every state would have 2. Winners of congressional districts would take that district only. (If one wants more delegates for a bigger party, then make make each district X and each state 2X.) Delegates would be pledged to the candidate winning their district barring late emergencies. There will be no super-delegates.
Any leading candidate will only be the automatic nominee if they secure 50% of the vote prior to the convention. Otherwise, the delegates at the convention will vote until one candidate has 50%, with the first round of voting narrowing the field down to two candidates unless one achieves 50% for a win.
1 (representative) vote per county... winner of the county votes gets the state’s votes.
NO OPEN PRIMARIES. PERIOD.
Arpaio for Chairman of the Republican National Committee!