Higher elevation running

So, currently (at home) I run between a 200 and 400 ft elevation. On June 24, I am running a half that's in our high desert at around 4,200 ft. I am wondering how this will affect me and don't want to head into it blindly. Any advice on running a higher elevation run?

If you can, I would try to arrive 2 days beforehand to acclimate to the higher elevation.  Otherwise, you could get elevation sickness, or at the very least, just tire out easily from the lower oxygen in the air.  I live at 4500 and people hike Mt Whitney- an hour away- at 14,500 elevation with many, many people having to stop the climb because they're too sick to go on.  Good luck!