For the most part, the Constitution is great. However, there are some parts of the Constitution that need to be amended and updated.
First off, we need to repeal the 22nd Amendment. The only reason that amendment was passed was so that FDR would always be the longest-serving U.S. president. A lot of people like term limits because they limit bad things politicians can do. But what if someday we get the greatest president in the history of the United States, one that everyone would love to re-elect to a third term, and we can't do so and are forced to select from two people who we know will be worse and possibly undo what the greatest president did?
Second, we need to make the Eighth Amendment more concrete. "Excessive bail" is an abstract concept that can mean different things to different people, and the same is true for "cruel and unusual punishment". An example of a concrete eighth amendment would have concrete limitations against certain types of punishments such as "Only murderers can receive the death penalty." I say this because it seems a lot of judges are afraid to set bails too high or give punishments that might actually deter future offenses because they're afraid their sentences will be seen as "cruel and unusual punishment". Well, ordinary law-abiding citizens vastly outnumber judges, and those ordinary law-abiding citizens are more afraid of becoming victims of crime than they are of judges giving "cruel and unusual punishment". What if someone you cared about was murdered in cold blood? Would you want the judge to go easy on the murderer? Of course you wouldn't. You'd want that murderer to suffer, and to suffer greatly.
Another thing we should do is lower the age to be eligible for the death penalty. If we lowered the age for death penalty eligibility from 18 to 13, we wouldn't be having all these terrible school shootings. China uses the death penalty more frequently than we do, and crime is much lower there.