Since a long time, even before I applied to become LHO, I've been trying to make newbies stay in MD. Another person doing the same was Fang Archbane, and I must say both of us were successful (the rate of people staying in MD increased a loooot). I dunno about Fang, but I personally would spend lots of time with them and guiding them with everything they should know.
As you may have already guessed, it is very time consuming, and sometimes I can't even give time to the actual newbies... and then alts come in. Can you imagine how pissed one can get after spending quite a long time and then finding out that the person you helped was an alt? NOT fun.
(Ravianna, Magistra's alt, was one of these people, but she got caught in my alt check. See below.)
Due to this, I devised a manual "alt-check" a while back, in which I seem to get a good idea if someone's an alt or not, and it does work. I check all of the newbies before I spend too much time on them.
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Basically, my point is that there are more than enough people in MD who are willing to help (notice I haven't even mentioned the LHO's in this post. Other than normal MD players, they are there too). Whichever newbie asks, his question 95% of the time gets answered.
From my experience (and I have a lot of experience with this) , those who want to stay in MD will definitely stay no matter what, and those who don't will definitely not. All we can do is make the realm more comfortable for those who want to stay, which is very important.