The moon is one thing, Mars is an entirely different beast.
The usual Apollo-era policy of 'land there, plant a flag, explore and return' will simply not work.
A radio signal takes 1.5 seconds to travel from the Earth to the Moon.
It takes 5 minutes to do that for Mars at its closest.
You need self-sustaining colonies at the minimum for any mission to be viable.
Jamestown, Mars anyone?
I just want to explain the sheer scale such a mission would entail.
NASA doesn't know a lot of things that will be needed for Mars right now.
They don't have the expertise to continuously supply an outpost in space.
They don't know how to grow food in completely foreign soil, in an atmosphere that is majority carbon dioxide.
They don't know how the human body will react to long durations in outer space.
01. My first move, if I were the administrator of NASA, would be to send a series of orbiters and rovers to return soil samples, and to record the general ambiance of Mars.
02. Concurrently, I would develop a space station in low-earth orbit, mainly for experimentation and to gain crucial knowledge for future missions.
03. Then, I would build a base on the South Pole of the moon, specifically the Shackleton Crater on the South Pole, where we have discovered water recently IOTL.
04. With the base I would build a space station in lunar orbit as a refueling point, for hydrogen fuel from the water we mine out of the Shackleton Crater.
05. Then comes another minute outpost in Martian orbit, where crews will change vessels to a specially designed landing module because Mars has an atmosphere (This will have to be similar to crew capsules in regular spacecraft, with disposable heat shields).
06. Then comes a colony in Mars. This can only be established after.
-> We know how the human body reacts for a long time in Space.
-> We know how the human body reacts to low gravity (not zero gravity. This is what the moon base is for apart from water.)
-> We know how to viably grow food in both lunar and martian soil.
-> We can sustainably produce potable water (That's simple enough, they recycle piss on the space station.)
-> We have good habitation modules for both the Moon and Mars.
-> We have good enough communication. Even so, the crew must have to be trained to be under radio silence for months at a time, for contingencies, of course.