My weakest area, at least IMO, is my chest. This is particularly true of the outer and lower portions of my chest. Any advice on improving this weak point would be appreciated.

Dips!!! Lots of them!!!
Think training's hard,. try losing!
Decline dumbbell flyes. Focus on the stretch and keeping your shoulders against the pads.
Thanks for the responses. I wasn't sure if decline flyes were a good choice or not, thanks for setting me straight.
And this is my current chest routine:
DB Bench 4x8-12
Jammer/Iso Incline Press 4x8-12 last two sets drop sets
Incline Flyes 4x15
Rotate every other week between DB Pullover and Cable Crossover 4x15
make sure your back is proper on the bench. try doing shoulder dislocations before your lift. yea, dips are great too, they are like an upper body squat.
If you are wanting to focus more on chest I would stick with dumbbells like you are already doing. My question would be are you doing drop sets every workout? You might be doing too much and preventing growth. 8-12 is good for hypertrophy but depending on how long you have been on those reps it might be time to switch it up. Make sure you can "feel" the muscle working. Get yourself in a position that you can feel the recruitment of your chest the most.
yeah its really simple....
pick exercises for your chest..the ones your chest most benefit from
pick exercises for shoulders that hit chest example high incline barbell, or dumbell.
front presses touch your upper chest
pick exercises for triceps ..example close grip bench press, reverse grip bench press, dips
Its been said, but weighted dips do exactly what you need. As does decline but I like extremely heavy dips.
if you have shoulder problems, lack the equipment or dips just hurt your shoulders, you can implement push-ups. great method for improving your shoulder health and stimulating chest, shoulders, triceps & core avoid having your elbows out on push-ups btw. this increases the torque on the shoulder joint and would defeat the purpose!
Couldn't agree more.
It's not always about exercise selection either though. Look at the exercises you are already doing and see if you are really getting the most out of them that you can. Focus on getting a deep stretch, and the best contraction possible. It's those two principles combined w/ the progressive overload of weight over time that's going to build a big chest. Adding two more exercises that your not pushing 100% on aren't going to cause much growth if any at all.
Weighted dips and more weighted dips....