You don't need to promote your portfolio! It's all a waste of time.
Better spend your time on producing stuff that sells, and it will cream to the top all by itself! 

I agree that you should concentrate the majority of your time on producing images to add to your portfolio.

However, I COMPLETELY disagree that you shouldn't promote it at all.

I promote my stock footage video portfolio like crazy and I have seen a HUGE return from my time investment on promoting it.

I started heavily promoting it 3 months ago and I have gone from zero referrals (and zero referral revenue) to over 40 referrals as of yesterday.  I've also had numerous sales directly attributed to my promotion efforts.

Again, your MAIN FOCUS should be on producing new images.  But if you're home all day (bad weather, bad hair, whatever) with little to do, spending some time promoting your work is not a waste of time.

As for methods...  It depends a lot on what your subjects are and what your target audience is.  For me, I actually paid $200 to do a mass mailing to 4000 television stations and small production companies in the U.S. and Canada.  Two weeks after my mailing I had $600 in sales (prior to my mailing, my best month was $90 in sales).  And I continue to see steady sales ever since.

I was talking about microstock only! The microstock agencies do all the marketing. And they spend way more than a few hundred bucks.
The only thing you have to do is make sure you end up high in the search results, and the only way to do that is by producing stuff that sells!

Again, I mostly agree with you.  However, like I said I don't think it would hurt.  If my stuff were of sufficient quality, I would probably mail a custom postcard to the illustration departments for all of the top print media outlets on a monthly basis.  One good EL sale would probably cover the cost.

And Microstock agencies market THEMSELVES, not their contributors.  It's important for you to get YOUR images in front of buyers.  If your stuff is not showing up well in search engines (or sites are monkeying with their search formulas {grin}), doing your own marketing might help.

In your case, your portfolios are probably large enough and of outstanding enough quality that you don't need to bother.  But others like the OP are not in the same boat.

I think it is a waste of time to promote your micro portfolio.

It is another different thing to promote referrals, something that can become very rewarding.