If you have large breasts, read this.

Ladies, let's face it: saggy boobs are unattractive.  They make you look old.  And they make your clothes fit all wonky.  There are plenty of beautiful over-the-shoulder-boulder-holders that will lift your lady lumps and give you some of your youthful appearance back.  Yes, all this with a bit of cloth!

I've had large boobs since I was a wee pre-teen.  My mammary glands have grown as I have, from a 36D in high school to a 40DD currently.  While not the biggest breasts on the block, suffice it to say, I've learned how to herd the girls and get them pointed in the right direction.

Sadly, many women don't.  I've seen it.  You've seen it.  Heck, you might be one of the women who struggles to find bras that will work for her, not against her. I hope this serves as a good PSA to tell that woman how to make her chest look attractive and presentable in spite of age and the forces of gravity.  Or to tell the woman who is ashamed or embarrassed by her large chest and is wearing bras that makes her girls look bad only serves to draw attention to her chest -- and not good attention, either.  As Tim Gunn is fond of saying, good undergarments are the foundation of good fashion.  Your undergarments need to do their job well so that you look absolutely fabulous!

Jody's 7 Rules of Breast Management:

1. Your bra must hold your breasts such that they fall between your shoulder and your elbow.  Shoot for the middle (you don't want to suffocate on your cleavage, but you also don't want to violate rule #2...)
2. Your nipples must face the world.  Nipples are not shy creatures, so they want to face the world head-on (so to speak).  Keeping rule #1 in mind, the natural "fit" for your breasts should be such that your nipples comfortably face forward while the breast is held between the shoulder and elbow.  Test where that is by supporting the underside of the breast, pushing up until your nipples act more like superstars than actuaries*.  That's where you want your bosom buddies to be when they're ensconced in your bra
3. Structure is your friend.  You're asking cloth to support a few pounds of flesh, so make sure that the cloth is up to the task.  That means (sorry, ladies) no elastic "barely-there" bras with spaghetti straps.  Leave those wannabe-bras to the A- and B- cups.  Those women have an entirely different set of issues to deal with.  Yes, you're going have to spend a bit more for a good quality bra with structure, and yes, you will have a few less options for bras, but you need more than a bit of lace and rubber band to contain and present your girls.
   
• Shoulder straps: Get a bra with comfortable straps that are 1/2" or wider. E Aho Laula** Not only will this help reduce the bra digging into your shoulder, your bra will last longer.
• Cups:  I'm a fan of the demi-cup underwire style, but you should choose a cup style that suits you. Demi-cups are nice because they give you a good cleavage bed and are constructed with lift and presentation in mind. Underwires really allow you a better selection of "pretty" bras with good structure, but if you hate underwires, you're going to need a bra that can compensate -- which means heavier material. 
  
• Band:  Depending on how large you are, you need a bra closure of 3 to 4 hooks.  Any smaller and the band won't be able to support the rest of the bra.  Larger might get annoying (5-hook bands are going to be about 3" tall, which can fold and be uncomfortable).  Remember, the band is the foundation of the structure of your bra, so it must be constructed well enough to do its job.
4. Know your size.  Not sure what your "real" size is?  You need 2 measurements (go ahead and put on your bra to do the measurements).  To get your band size, measure under your arms, high on your back, across the top of your chest. If this measurement is an even number, this is your band size. If an odd number, add 1" to determine your band size. To get  your cup size, measure loosely around the fullest part of your bust. Next, subtract your band measurement from your bust measurement.  Each inch represents a step up in cup size. My band measurement is 40" and my bust measurement is 45", making me a 40DD. (A, B, C, D, DD, DDD, F...)
   
5. Know when your bra fits.  Sadly, most lingerie departments are not staffed with knowledgeable people who can truly assist you with finding a bra that fits.  They might be able to do your measurements, but that's about it in my experience.  If you go to an upscale shop or a store that specializes in bras, you might find someone to really assist you with bra fittings, but you're going to be on your own for the most part.  Don't be afraid of wiggling and adjusting your breast so it fits into the cup correctly (i.e., make those nipples point forward!)
   
• Closure:  You should be able to comfortably, but snugly, close the bra on the last set of hooks (largest band size).  Bras are mostly elastic, so expect it to stretch out as you wear it.  Resist the urge to wear the wrong size band because the number is scary.  You also do not want any spillage over the top of the strap in back.  That indicates it is too small.  And while 8 in 10 women are probably wearing the wrong size bra, you don't need to be one of them.  Wearing the wrong size bra is as bad, if not worse, than trying to squeeze into size 10 jeans when you're really a 14.  It looks bad, it's uncomfortable, and it is silly.  Don't define yourself by a number!
• Straps:  Don't forget to adjust the straps!  Again, the straps should be comfortable but snug.  You don't want the straps to dig into your shoulder, nor do you want them slipping off.
  
• Cups:  Your breast should be contained within the cup.  This means no boob spillage out of the sides, bottom, or top.  If you have spillage, try one size larger cup, or the same cup size and one size larger band.  You also don't want gapping between the top of your breast and the cup or the front of your nipple and the cup.  If you have gapping, try one size smaller cup. You might also fit into a smaller band larger cup (e.g., 40DD -> 38DDD). Also, the shape of the bra might not fit the shape of your breasts.  
  
• Overall presentation:  Wear a thin t-shirt when you go bra shopping.  As a final litmus test, try the bra with that t-shirt to make sure that your girls look good.  Are there any lumps or bumps?  Do they look natural?  Do you have "wrinkly boob" syndrome from the embellishments (lace, beads, etc)? "3rd boob" syndrome (the material between the cups tips forward to create a lump that looks like a middle boob)?  Try different styles so you get the best presentation possible.
  
6. Try it before you buy it.  Not all bras will fit the same way, so it is imperative that you try on the bra to make sure it fits. This could mean going up/down a cup size or band size.  In some models, I'm a 42D, in others, I'm a 40DDD.  It all depends on how the cup is shaped and the bra constructed, so don't be afraid to try on different sizes.  Like you do with most clothing, use your measurements as a starting point and adjust up or down as necessary.  I suggest buying bras online only after you've found a brand, style, and size that you know fits you.  Otherwise, you run the risk of wasting money on shipping when your bra doesn't fit.  Some bras won't look right.  Some will be uncomfy, painful, and just ...wrong.  It's ok to say "no" to a bra that won't work, regardless of how cute you think it is.
7. Take a friend/sister/mother with a good-looking rack shopping.  If she has figured out how to choose the best bras for her breasts, then she's the one you want with you on your shopping trip.  She can help you look at bras with a critical eye and employ all these principles to make your girls the envy of the breastulated world!

*How do you tell if an actuary is outgoing?  He looks at your shoes instead of his own!
** Wider is better!