There is more than one Mt. Humphreys in the US, I believe.  If we are talking about Mt H, the highest point in Arizona, just north of Flagstaff, I can offer some advice based on numerous ascents, most of which were solo.

Depending on conditions and season, the difficulty may vary enormously due to snow and cold, but it is basically a straightforward hike, with no technical difficulty.  The most straightforward route is a drive to the Snow Bowl or thereabouts and head uphill. You eventually reach timberline and the ridge overlooking the Inner Basin.  From that point continue northwesterly up the ridge, enjoying the view, until you reach the summit.

I believe that now some climb from the Inner Basin, which was closed to entry in my day.  Hopefully there will be comments by more recent climbers

Unless you encounter severe conditions - a heavy snowpack and cold, a hike to the summit is a good trip, if you are beginning your alpine career (and even if you are not!!)

Altitude may be an issue, especially coming from Phoenix.  Get some previous exposure to altitude, like hikes on Mt. Lemmon or Mt Wrightson (near Tucson).  Spend a day or two in Flag to begin acclimatizing and heed the mantra, "Climb high, sleep low.'  Maybe drive up the hill a bit, look around, and then descend.  Don't expect to set any speed records.

Just general hiking, cycling, or running will give you the necessary fitness, but you may still feel the effects of altitude, regardless.  

Conditions can vary considerably.  In the spring, you may encounter deep snow or bare ground, depending on the snowfall received.  Watch the weather report and be flexible.

I worked near Flag for several years.  I have stayed at my inlaws house in Flag, climbed the peak and returned by noon and mowed their lawn in the afternoon.  That's a summer excursion.

On the other hand, on my first ascent in December, we were training for later climbs of the Mexican volcanoes.  We spent the night at the Snow Bowl in -40F temps.  I alone reached the summit since I was the only one with snowshoes, which I abandoned on the descent, thereby spending the most miserable night of my life huddled in a snowbank, exhausted and waiting for dawn.  What undoubtedly kept me injury free was the small stove I carried, a last minute decision.  

Like nearly all mountain ascents, an early start is recommended.  Weather on Mt H typically worsens in the afternoon.

 

Have fun and let us know how it goes.....

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