This has been a pet peeve of mine for quite some time. What with all the resources at our disposal It breaks my heart everytime I see some badly drawn boobies. Here in the 21st Century there's simply no excuse for it anymore. Beginners get a pass, but on occasion I see artists who are far more accomplished and certainly more productive than myself who draw boobs badly. Seeing as how it is such a subject of heavy focus in the industry I feel that it's necessary to do my part to inoculate against the tsunami of badly drawn boobs. So here is a primer or visual howto that you can print out and laminate to carry in your wallet whenever you aren't sure whether you're drawing boobs well or badly. Although boobs come in all shapes and sizes, this is the basic model of beautiful boobs that I go off of as a starting point. You can alter it to fit the needs of the drawing.

As you can see I've picked a standard 3/4 shot for some depth and here we go.
➙ There are direction lines to illustrate how the boobies beget from the rib cage. We see ➊ how they connect to the manubrium at the top of the sternum and descend away at a 12° angle. ↙↘

➙ You see a second descending line ➋ beginning at mid clavicle and descending (this time) inward toward the bottom of the sternum ending above the Xiphoid Process. ↘↙

➙ Line ➊ illustrates how the boobies curve around the rib cage. Line ➋ shows how you begin your holding line at the clavicle, descend inward, follow to the outer medial rib cage and returning to the north most peak.

➙ ➌ Points to how the boobies come forward at a slight downward angle lending to the illusion of weight, heft and depth. At the end point is where you would overlap the nipple and areole. No doubt about it, these boobies are 3 dimensional. You can nuzzle them against your cheek, let them rest on your face and motorboat to glory!

➙ ➍ is probably the biggest repeat offender in all of the realm of boobie drawing. This squishy tissue of where the pectoralis lays underneath the boobie and is squashed up against the bicep. Critical to drawing an appealing boobie and yet omitted by many beginning artists (even myself). It follows the inside arc of the deltoid and then S curves inward completing a nice rhythm abutting finally at a T against the boobie.

➙ Other miscellaneous notations; regard the seams of the rib cage and how they continue on to the waist and hips. You can see how important having a three dimensional torso is to complete the illusion of soft, warm, safety inspiring wagamamas. You can also see the same construction lines on the neck and the rest of the torso. Our headless horsewoman is fit without being fat free. Any more muscle and she'd have less boob. Any more fat and she'd stray from the classic 36/24/36 proportion that evolution naturally selected into us to as a sign of health and reproductive viability.

In closing, look for badly drawn boobs (particularly by good artists) and try this method and see for yourself what a difference it can make. I hope I have added to the sum total of your drawing knowledge and I eagerly await your submissions of reconstructed boobies. They are so important to the successful allure of your cheesecake and fantasy women.

Good Drawing and good day.