But alas....

I do know that some MPs do train their gals on the job.  In fact I have received discounts from a local MP who asked me if I'd be willing to be a student's practice for some part of my massage.

There are some decent books out there as well, the most famous being the Joy of Massage, which I have read and found very instructive.

The gist of a good massage is firm (and for me, deep) pressure in the right places, and long enough to lose one's self in it.  (I like at least an hour, but I know that is rare.)

You might also look into getting a massage or two from a really good spa, and taking notes on what feels really good.  That's essentially how I learned to give massage, and from what the gals tell me, I'm pretty good at it.

Kudos to you for wanting to learn.  I love massage and hope the trend grows

I also learned by doing.  Techniques my recipients liked:
Stretching the muscle groups...  stand or kneel so you can use both hands together use you weight to push down firmly but not hard...  you can use the heels of your hands to push away across the body/musle groups.  You can use the fingers together to stretch the muscles on the return stroke (pull toward you).  
You can work from either side, over his head if he's on a Massage Table, or kneel over his legs to work his butt & lower back...  
 
Arms & shoulders mainly can use a squeeze & release techique on a muscle group.  2 hand togther cupped over the muscle, squeeze & release.  Useful for relieving "knots" & tight muscles.    

A Fav (now retired) was a LMT, did the whole spa routine.  Dim lighting.  Music, warmed the table with heating pads in cool weather.  She used unscented candles, lest a scent linger.      

The Professional Training of a LMT takes quite a bit of time & hours of supervised practice...  but  
Probably everything these days can be found on-line.  I did searches & found lots of links.   I'd read everything you can...  and offer a "free" 10 minute massage to your existing clients.  I bet no one declines.  Extend their appointment by 10 minutes.   Most guys will not complain about anything you do that involves touching but I suggest you pay close attention to the soft sounds & his movements...  if he really likes something he'll (I'll) move slightly to get more of it.  Different people have different preferances but if someone doesn't respond to something move on to something else or say explain you'll try something else.

http://www.wikihow.com/Give-a-Back-Massage  
http://www.wikihow.com/Massage-Your-Partner
http://www.sheknows.com/love-and-sex/articles/805054/6-steps-to-a-sexy-massage  
And more...

Maybe I'll wander up north with your pointer leading the way

It's like $18 on Amazon right now for the paperback.  I've got a first edition from 1992 so it might be time to get the current, third, edition and see what's improved!  My use is strictly recreational, and learned by practice.  Here's the book's library numbers:
ISBN-10: 0983402191
ISBN-13: 978-0983402190

Most striking thing I learned was to never break contact during massage: once you start touching, a part of your body always stays in contact.  Breaking contact leaves the person feeling abandoned, and this provided an explanation for sessions when I'm receiving and felt uneasy/confused/worried when contact stops.

I'd recommend to pick a book/body section and focus on that with a willing subject.  Bonus points if they'll agree to provide honest verbal feedback during or after.  And not every massage has to end with an orgasm.

I'm stunned by how nice an entire forearm feels running down my back, or up the inside of my legs.  And when any stroke continues over the cock & balls, without focusing on them, it can lead to an amazing session.

Random trivia - inner thighs work like a penis pump for me; the more you work that section the harder I get.  The girls at my local AMP laugh about it, because even on days when I just want massage they can get me up & down at will.  They'll do inner thighs for a rise, then back to feet for the drop, and repeat until I either ask them to knock it off or to finish what they started.

Is maintain some contact.  I love nothing more than to feel body warmth...  contact with the provider.  It's what makes the connection for me.  
You can lean against the table...  I often scoot towards the side she's on...  be creative...  
From the top, make contact with his hands, arms head.  
From the bottom, his legs or feet.    
Some gals can get on the table too...

Practice,practice,practice......

I am always available as your subject!

from providers I know who excel at massage, and from my own experience in learning sensual massage:

- try to find a local massage provider who's an expert at massage (LMT, her reviews) and ask if she'd be willing to give you a lesson or two--either paid or barter arrangement. And ask if she'd be willing to let you observe a session or two.  Of course the clients would need to sign off on it, but I'd have no problem wth such a request and I bet a lot of other guys wouldn't have any problem either.  
- if you haven't received many massages, go see some therapists who employ different techniques and pay attention to what they do. I've learned a lot about massage just from picking up techniques from therapists over the years. You should include some FBSM sessions from providers who accept female clients.  
- check YouTube etc for how-to videos on sensual massage, tantric massage, lingam massage (and if you'll have female clients, yoni massage). I've learned a lot from such videos.  
- when you start out, ask prospective clients how much experience they have with FBSM. You can get a sense for this from their review history. And if they're willing, ask them to give you feedback and coaching during the session, maybe in exchange for a discount or extra time. I've done that before for some new providers; I told them up front that there would be no review, so they were more willing to try new techniques.

I live near DC... would be glad to receive and share pointers... the one I heard above that really strikes a cord... always maintain at least a hand on them somewhere... contact all the time... is important.....