What would be a few beginner mistakes to avoid in piping? I’m trying to form some good habits from the get go.
too much tension with shoulders,arms and fingers ,bad playing position effects so that u loose the “overall control” of playing.
Not having your set checked by an advanced player.
I would second the cautionary note on too much tension. That’s the easiest one to pick up and the hardest one to get rid of.
Like Frankie said, “Relax.”
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Buying a full set.
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Buying a Pakistan-made set of any kind.
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Messing around with the reed one day after buying the pipes because it is making squeaking noises.
Mukade
All of the above plus…
…learning in isolation.
Find a piper or three…whether they teach or not.
The internet is not a replacement for this…
Leaks in the bag and bellows
Things to avoid …
Spending more time on piping forums on the internet then you do on pipe practise! 
Also, as a beginner I think you are better off playing 15 min a day than an hour and a half on the weekend.
Thats my experience, but hey I’m still a beginner.
/MarcusR
All of the above, and
in the absence of a live tutor/mentor; at least get hold of the NPU DVD Vol 1 - The Art Of Uilleann Piping. Explanation of the rudiments are to be found there. Get those right at the beggining and you will be well on the way.
Good luck - and remember, if others can do it, so can you.
All of (all of) the above, and not doing a f^&*ing search. 
Thanks for the great replies. They were really helpful.
One mistake to avoid is using the fingertips to play the chanter. This is quite common in people translating over to the pipes from the tin whistle. Use the pads of your fingers instead, and your piping will come along far quicker. 
Cheers
Steve
The first bad habit that beginers make is thinking about take up the pipes. After that, there is the taking up of the pipes. Take up smoking or drinking heavily instead…maybe blindfold yourself and run around with sharp pencils in your ears.
Beginning–the biggest mistake you can make and the hardest to correct.
The sorts of mistakes beginners make is often a product of what instrument they are coming to the pipes from.
Unless coming from other bellows-blown pipes, they struggle at first with the bellows. They may try to control the bag pressure with the bellows, rather than with the bag arm. They may use rapid pumping of a half-full bellows rather than fully filling the bellows and making fewer, but more productive, smooth strokes. It will take a while for the bellows to become automatic, and for the air supply to become dead-even. (Practising playing long steady notes rather than trying to blast through tunes will help the blowing issues.)
If coming from Scottish Highland pipes, they will use an incorrect grip on the top hand and play many inappropriate ornaments.
If coming from orchestral woodwinds they often try to use bent fingers.
In general, beginners in my opinion try to blast through tunes before they have a basic competence on the instrument. I have beginners play scales (using both C natural and C sharp) and arpeggios such as:
Bottom D F# A backD highF# highA and then back down.
Bottom D G B backD highG highB and then back down. etc.
I have them repeat notes four or five times each with a silence in between, beginning with hard bottom D and working up the scale to high B.
When they have a basic mastery over these things, it’s time for tunes.
Learn to play tunes slowly, very slowly. Many try to bring up to speed to quickly which leads to sloppy playing technique and hard habits to break. Better to learn a few tunes well than many badly. Only bring up to speed gradually, after achieving perfection and perhaps even after adding a few ornaments. This is the most common thing that I have consistenty heard from teachers through the years.
Best of luck. Try to be patient and enjoy. Despite the surlness here and there, this instrument is beautiful and rewarding.
Neil