If you can't draw breasts, then you can't call yourself an artist.
But you can't start at the top: if you can't even draw an egg, then breasts are always going to be beyond you.
Artist Michael Newberry's mini-tutorial on the difficulty and importance of drawing form -- "no spectator is going to believe that the woman's breasts were concaved, or that the sphere was flat" -- offers the perfect instruction on the technique needed.
It all comes down to letting the feeling become form ...
Figure below is a study for Newberry's 'Kimberly,' in pastel.