I think the main thing is initially isolating the practicing of the bellows from playing tunes on the chanter.
Might be best to take out the chanter, cork it off, and begin by playing with only one drone. This has the advantage of you not being tempted to noodle on the chanter when you need to be 100% focused on the bellows.
Then, after you can hold that one drone absolutely steady for a few minutes straight (which could take weeks) add a 2nd drone. If you're new to piping this is invaluable learning time, because you can practice tuning the drones to each other, getting your ear used to listening to the beats.
Then get all three drones going. It's much more difficult to tune all three drones together than just two. Once again time practicing tuning the drones is invaluable to your development as a piper. (Some very good pipers don't have a good enough ear to tune their drones while all three are going.)
After you can keep the drones going dead-steady and tune them to beatless perfection, I would shut them off and start using the chanter alone. If you're not an experienced piper you'll get all sorts of squeaks due to imperfect finger placement leading to leaks around one or more of your fingers. Bag-pressure fluctuation also can create squeaks which is exactly why you should be able to play your pipes with dead-steady pressure BEFORE you begin playing upon the chanter.
Chanters are much more finicky about pressure fluctuations than drones (which is why I advocate doing drones first) and Border pipes chanters are much more finicky about pressure fluctuation and fingering precision than either Great Highland or Scottish Smallpipe chanters- if you're new to piping you've chosen the most difficult instrument first (like the person who goes for his Doctorate before getting his Bachelors). So you should start with a note which requires fewer fingers on the chanter, say F# (only requiring the thumb and one finger) and try holding that note for a few minutes with no fluctuation. Then you can play various Long Notes, holding E for a few minutes, D for a few minutes, and so on, working your way down the chanter. Low A, on Border pipe chanters, can be finicky and can squeal or change pitch with a relatively small change in bag pressure.
It's critical to ONLY play Long Notes until you can hold any chanter note dead-steady for as long as you wish. Once this is mastered it's time to bring in one drone, practicing tuning it to the chanter, and when that's mastered a 2nd drone, then eventually the 3rd drone, training your ear as before.
When you can hold any note on the chanter perfectly steady, with all three drones going and everything in tune, and operating the bellows is a completely autonomous activity, it's time to start playing scales and simple tunes. Jumping the gun and having fun blasting through reels and jigs before you know how to blow and tune the pipes will lead to being an unsteady and out of tune piper.
About bellows technique, the main mistakes beginners make are:
1) using short choppy or jerky motions, not using the full capacity of the bellows, and
2) trying to control the bag-pressure from the bellows.
The bellows are ONLY there to fill the bag. All of the pressure-control comes from the bag arm, just as it does with mouth-blown pipes.
Before a bellows-stroke you lift the elbow of the bellows-arm so that the bellows fill to their capacity (like taking a deep breath) then do a smooth but forceful stroke to fill the bag. The bag-arm has to lift to allow the air to enter the bag without making the pressure spike.
The air is coming into the bag from the bellows intermittently; the air must be fed to the reeds steadily; and the bag-arm is the pressure-regulator that makes this possible.
If your bellows have decent capacity and your bag, pipes, and reeds aren't leaking you don't have to do bellows strokes very rapidly; it' a relaxed purposeful action, not a jerky one.
With both mouth-blown pipes and bellows-blown pipes the beginner's first stage of bag steadiness is learning to even out the tone of the bag-arm-squeezing period and the blowing-air-into-the-bag period. First the two periods will be at different pressures, like this
Once these two are evened out a more subtle problem usually becomes evident, that of having a spike or drop in pressure at one or both of the junctures between the blowing and squeezing portions, perhaps like this
where perhaps there's a spike in pressure during the transition from squeezing to blowing (due to the bag-arm not coming off the bag soon enough, in this example).
Or the opposite, the bag-arm coming off too soon, leading to a drop in pressure at the same point in the cycle.
1978 Quinn uilleann pipes
1945 Starck Highland pipes
Goldie Low D whistle