This can be done graeme_p, but even then you need to ALWAYS look over their shoulder (college students) to make sure they doing them right.
Give them a list of which anchor text you want them to use, and what url. I would start off with maybe 3-5 and let them do some comment links. You need to teach them how to look at pagerank on a blog, to make sure it's not penalized (I don't care if it's high pr or not--just has to be at least a pr1, anchor text should matter, if it is theme related). Of course, higher PR is better.
Teach them to look for theme related blogs, for example, "health" and to how to check to see if they are dofollow. In my opinion, I would never just do comment links.
Have them do the next five in articles, that they or you create with the links in it that you suggest.
Teach them how to do five signatures in forums. Put a couple of images in your siggy with keywords in alt text.
A big thing, in my book, is not to have all the links start with, "health", for example in the anchor text, mix up the words so that sometimes the word health is at the end of your keyword phrase or in the middle.
I would do maybe five directories, myself, since they have been scrutinized by google. I believe yahoo can build trust rank for you, so that one is a must.
If your site is new, start out with five links the first month. Most of my sites have been around for 7-10 years, so usually 20 links a month is adequate to keep it where it is or slowly move upward in serps. I've been front page of google for many keyword phrases, and my goal is to stay there, and 20 links is good for me. Trouble is, if you do too much link building, you can move down in serps.
It's late, so I apologize if I am all over the place with this post. In a nut shell, 5 each, comments/blogs, directories, articles and forums. Have 4/5 keyword phrases, repeat the most important one exact keyword phrase 3-5 times in anchor, mix up the rest. Don't put main keyword at the beginning of every link. Don't sound spammy in comments. Check pagerank, whether links are dofollow, and check on them every so often, to make sure they are doing links right. From that first batch of college students I still make about 10K per month on their efforts. They did 18 per month for me for about six months.
One thing I did was go to a few popular webmaster forums, buy a bunch of cheap link lists and go through them. Many and I mean many did not work, were spammy, but what I did find was a gold mine after working through the list. I think I paid maybe $10 for each list. Some of those links were high pr, off topic and had tons of spam links. I would teach them to avoid that kind of post or thread like the plague.
Oh and have them look for edu and gov links. That's how I did it, not sure how it will work for others. Apply whatever works for you. :)
Again, it 2 am, and I'm heading to bed. Was afraid I wouldn't get to this tomorrow. Oh and one more thing have them to an excel spreadsheet keeping track of date of the link, type, url that link was submitted to, keyword phrases, maybe pagerank, then compare... if you find a combination that really works well, you'll want to know exactly how you did it. Good luck