Homing Attack. Don't use it.
The sad thing is, it works. At least for me; my opponents don't deal with HA properly. If they know the match-up, HA should almost always fail; you have to be really careful when you use it. n00bs will shield the hit (you'll often bounce away safe enough to not be punished), but they're better off rolling or spot-dodging so they can easily punish.
Never, ever, ever use HA if your opponent is close to the ground, but you're high enough above that if it misses, you'll fall into that clutching-the-ground lag. That should never happen, you just have to learn what zones of the stage are safe; so you'll happily bounce off the ground if it misses (which restores your 2nd jump btw!), or your landing will be lagless.
Bad HA: You get in the habit of sometimes breaking out of SDJ with HA as a "cool fake-out" approach. These random HA's will punish a panicked C-sticker, but your opponent has a zillion options if he expects your approach, or knows to just wait and respond.
Good HA: You're actually sure to bait a laggy attack before you charge the HA. Note that an attack has to be really laggy if you can respond with a HA. In which case, HA is useful since it kills whatever momentum you had before, so you use it when you've baited but are travelling away from your opponent.
Bad HA: You're off the side and returning to the stage, where your opponent is waiting from the ground; and your 2nd jump is gone. If you're at the height of the stage or lower, an unlocked HA will force your spring to be punishably low and close to the stage.
Good HA: A recovery option when your 2nd jump is available (so you're OK if it doesn't lock-on), and/or you're below the stage so that it will hit the stage bottom or side (FD and Yoshi's Island are good for this); so you get close to the lip with your spring available, which gives you enough options to get back safely or bait some gimp attempts.
Turnaround-B: Learn to turnaround-B the HA. It definitely helps when you have your back to the stage.
1. Opponent is on the stage, and you're trying to recover; HA towards the stage so if you miss, you're not totally doomed.
2. You're aerial-chasing opponent off the side; you'll be close enough to the opponent that they'll still be in range for a backwards HA, but if it doesn't lock then you're doomed if you didn't turnaround it.
3. You're on Yoshi's Island with those crazy walls. You can safely recover with HA here since it can happily bounce off the walls to bring you up, even without locking onto the opponent. Note that if you're right up against the wall, the HA can face away from the stage but still bounce off the wall... but you might as well turnaround it since it gives you more leeway for the wall-bounce.