Excellent article! As one who is an active instructor in other fields, and who intends to someday have his own dojo, I really appreciate articles like these!
The thing I like the most is the simplistic approach - it's really not that hard to keep students (although that may be different for Aikido, but I'm not sure why it would). Getting them, yes - keeping them, no. If I may, I'd like to drop my own 3 rules in to be picked over.
(OOPS - QUICK EDIT! The article was about looking for a dojo. I wrote 3 rules for instructors when dealing with newcomers. Me bad!)
Rule number one in my book is make it fun. (Actually, Rule Number One is 'Make it safe', but that should be so basic as to not need mentioning.) Students need a reason to stay, and while a desire to learn is very important, if a student isn't enjoying him or herself, he or she (I'll stick to one gender from now on) will NOT return.
The Sensei's third point I personally consider a corollary to the first: care for (i.e. involve) the newcomer. Nothing's more boring for a newcomer than to just sit and watch, he wants to learn! If I had a dojo, I would introduce a newcomer to the ki exercises 1st, reason being, you provide the "that's COOL!" hook right away; showing the student (and having him try) things 10 minutes ago he would have sworn were impossible. Get him up right away, get him involved, get him saying "Oooo!" (worked for me, at least - I spent 5 minutes trying to bend our Sempai's Unbendable Arm. She's half my size, half my weight and has about 15 years on me. I had to just walk away for a minute shaking my head, speechless. I was hooked!
Of course, involving newcomers immediately may divert more experienced students away from their own levels, but it's a worthwhile cause - gets the newcomer moving and gives a higher level student good practice at instruction. There are always exceptions, of course, but my rule # 2 would be "The newer the student, the higher the priority for training".
Rule number three is almost always forgotten while a new instructor is refining his trade: A newcomer is a person outside the dojo! I'd better explain: The one trap almost all new instructors fall into is "I am the instructor, you are the student. I know all, you know nothing". Sometimes, an instructor will sort of seem to think that the newcomer just materialized outside the dojo's doors with no knowledge, experience or ideas of his own. I've done it, my instructors all did, I'm sure many reading this have as well. It's something we can chuckle over once we've learned better. Thing is, if a newcomer is faced with this, he may well decide the attitude isn't worth it, and look elsewhere.
NOTE - I've yet to see this at all in Aikido from an actual instructor. It seems the generous, tolerant nature of the art prevents this mistake from happening - kudos to aikido!
So, to sum up, my 3 rules:
1) Make it fun.
2) The new student gets training priority.
3) Respect the newcomer's life/knowledge outside the dojo.
Hope this rambling post helps.