Heh, I learned how to time my aerials and fastfalls as Falco thanks to having Pika as a secondary. And general advice is always the best type of advice :D
@Dre: If you're having trouble against spacies' shield pressure...the best bet is to not get trapped under pressure in the first place
but otherwise, escaping is a bit tricky. Wd Oos or Uair/Nair Oos is pretty good if their pressure isn't 100% airtight, and are probably the fastest and safest escape options if you're under shield pressure. For the record, never never never try to shieldgrab spacies out of pillars. Only mentioning this because I used to do it on instinct all the time...T_T the timing for getting out without getting hit is tricky to get though, especially if your opponent is mixing up their pressure timing/attacks.
If you're having trouble landing an approach (or the approaches you're trying aren't working), you'll have to force yourself to play a little more conservatively, figure out why your approaches are being shut down, and capitalize on any opportunities/create openings for yourself. If your opponent is playing as aggro as you imply, your best bet is to bait an approach (as Kage stated) eg. I only recently started doing sh wavelands for baiting/spacing, and it's amazing how often people fall for a backwards waveland if you just throw it in the mix of nair approaches every once in a while. Remember that aggro players tend to be a lot more impulsive than the average player so try to figure out different ways to bait them. If that's not working, it means they're probably taking advantage of something repetitive you're doing in your approach.