Hindsight being 20-20 I can identify exactly 3 mistakes that The Gipper made during his time in office.
1) Appointing Sandy Day “Affirmative Action should be fine for...oh, let’s say, another 26 1/2 years” O’Connor to SCOTUS
2) Pulling the Marines out of Lebanon and turning tail after the truck bomb.
3) Taking “low income” people “off the tax rolls”.
There were plenty of people at the time counseling him against #3.
#4) Giving up on his plan to abolish the Department of Education.