Lifting or lowering your chin is how I was taught to HELP with pitch adjustments. Each player and each instrument has unique tendencies on pitch. For instance G2 for me is ALWAYS flat. If I lift my chin slightly it changes the airstream enough to correct the pitch.

I am not entirely sure what you mean by blowing into or across the hole. No matter how you look at it you are effectivly blowing across the hole. You should just practice a note over and over until you get the absolute best tone you have heard. Once you have heard that tone try to remember what it feels like and keep that tone as you move around to different notes on the flute/picc. Perhaps someone else can offer more tips on this?

I am glad the tips you have received so far have helped. Keep working on it! Piccolo is such a rewarding instrument if you work on it!

When I play Piccolo, I like to tune to a note such as middle Eb whose pitch is dependent on more of the length of the piccolo than Bb or A. It is easier to change how you blow to bring a Bb or A into tune than an Eb. This has the consequence that if you simply tune to Bb it can be practically impossible to bring half the notes into tune. Sadly, many bandmasters dont understand the physics of the flute and consequently blame the players instead ...

I listen closely to trumpets and clarinets (usually playing much lower notes) with the aim of maintaining good tuning with them rather than flutes or other piccolos which are not necessarily reliably in tune. If you play confidently and loudly in tune with the other sections, other flute and piccolo players will hear you more clearly and be more aware of their intonation.

There some notes on most flutes and piccolos (not always the same ones) which are intrinsically slightly out of tune. Playing with a tuner can help but in practice this is no substitute for playing in an ensemble when especially brass instruments have certain harmonics out of tune and most music sounds better if certain chords have sharp or flat 3rds, 5ths etc.

Well it's now good to know to listen to the trumpets and such for tuning because everytime I listen to the other flutes and piccolos I adjust it to be in tune with them and I'm OUT of tune with the other sections.

Let me explain the "blowing in or across the hole" thing...Some lady that was a flute teacher (not my teacher though) told me that I needed to make my upper lip come over the hole so when I blew the air would go down into the hole. She told me not to keep my lips even and that the upper lip needs to be further out than the bottom one. She said that the air should go directly into the hole and that we shouldn't blow the air across the hole because it will "waste air".

I tried it but I ended up continuing to blow across the hole with my lips even because I couldn't get a good sound blowing "into the hole"...I've just always wondered if I'm doing it wrong.

Your lips are going to be different from everyone else's, so what works for one person's embouchure will not work for everyone. I play with my lips even. Simply by having the piccolo pressing against your lower lip, your air will be diverted downward. You really don't want to blow either across the hole, or into it. You need your airstream to strike the far side of the embouchure hole. This sets up vibrations in the air column, and produces the flute's basic tone. Blowing down would seem to me to mean that you are bypassing the air reed (far side of the embouchure hole) entirely, and simply blowing into the tube, which will not make for a very pleasant sound (if it produces one at all), while blowing straight across means that a lot of the air is going to be wasted. You need to be aiming somewhere in between, so that your airstream is split by the air reed. Finding the proper angle will give you a good tone, as well as help you conserve air, because less will be lost over the top of the hole, or down directly into the flute. As for this raising and lowering your head bit, I would say to avoid it if possible. As Dottedeighthnote mentioned, if you know one particular pitch is problematic in a particular passage, go ahead and lift or lower your head (depending on which direction you need to go) for that particular note, but it should not be your default way of adjusting intonation. It sounds to me like a different way to get the same effect as rolling in or out; rather than moving the flute, you are moving yourself. Primarily, you want to adjust the air angle, velocity, size of the airstream, etc. to adjust intonation, and then if you need just that little extra that you can't get with your air, you might consider raising or lowering your head. It's really not that difficult to change pitch as much as a half step either direction using your air, and learning to adjust using only your mouth/air will make things a lot easier for you in the long run.