What is the most difficult aspect for developing new recruits upon arrival to their new duty station?

I take 2 different views at this.

When I first arrived at Minot I was treated as an outsider. I was told what I needed to know before going out to an ICBM site. I was basically thrown to the wolves, so to speak. Needless to say, I totally screwed up my first site inspection of an alarm call. The flight sergeant chewed my ass like a piece of gum. My mentor didn't correct me, didn't teach me anything. My flight sergeant, when asked how I could improve, did basically the same thing - there may be other issues behind his actions, though.

My original mentor has been assigned TDY during my hiatus between tech school & assignment, so I was picked up by another mentor that didn't really want me "tagging along". I felt like I was run out of the squad. I ended up getting reassigned to the armory where I excelled. I had leadership that mentored me & gave me responsibilities that pushed my perceived limits.

As a civilian police officer, I became an FTO (Field Training Officer). I took those lessons learned from the Air Force & implemented them in my training style. I made the new officer fresh from academy feel as though they were wanted. I gave them just enough responsibility to push them until they could handle more. The last thing I wanted to do was to alienate them or make them feel as if they were outsiders.

The most difficult aspect would be accepting new recruits "into the fold". If this is not done, they are chased away & can become the weak link in the chain of your squad/flight.