Health Niches
OP, health is a great broad niche. There are lots of ways to monetize, and lot of permutations, so to speak, let's say:
SITES:
A) Great website, usually on it's own domain, informative and
original content (photos, infographics, apps, articles, etc). Usually has
any or all of the following: Main Site with articles, Blog, Forum, Online
Store.
B) Good website, informative, usually on it's own domain or a
sub-domain, with well spun or somewhat borrowed/PLR content. Usually
has any or all of the following: Main Site with articles, Blog.
C) Kinda crappy website, web 2.0 property, lots of spun or shamelessly copied content. Usually
a blog.
D) Downright Spammy.
Monetization:
1) Great Health Related Products (Amazon, products you resell,
affiliate accounts) incl. books, vitamin supplements, videos, even shoes
and other gear related to health and fitness. Convert OK for type A and
B sites
2) Not so Great/OK products (clickbank, cheap versions, generic
supplements, hyped supplements ie. moreniche's). Convert OK for type
A and B sites
3) Hyped (downright useless or doubtful/poor benefits products), usually
very expensive and with great comissions. Also prone to shady trial
offers. Convert GREAT for all sites, BUT will burn their reputation to
the ground
4a) Good Contextual Advertising (Adsense), works great with type A sites, good for B sites, avoid anywhere else.
4b) Contextual Advertising (ie. Chitika), works mainly for type A/B blogs
4c) Contextual Advertising, crappy edition (ie. AdBrite). Avoid, ruins everything it's put on.
5) Self hosted and managed advertising. Great for A sites, good for B sites, you won't make a sale for types C or D sites,
unless you offer it to DP noobs (and that's evil and will destroy both your and your site's reputation)
As you can see, the combinations are almost endless. I could spend hours writing about this, I know I'm leaving a lot of things out, but I hope this serves as a very general guide. As for promotion and SEO, just read around and experiment along the way.
Note: Depending on the niche, there's also a sixth type of monetization, examples can be found in body building sites. Not worth the risk. AVOID Every time.