Do you push or pull your weld puddles?

It depends on the situation.
If the metal is thin, I always push the puddle about 5 or 10 degrees and ''whip'' the weld slightly (about 1/8'') much like you would do with a 6010 arc welding rod.
Why?
I have two reasons for this.
First, it tends to clean the metal you're coming to, and secondly, it prevents a situation that mig welds are known for which is ''cold lap''.
Also, I run the most voltage possible without the wire burning back to the tip, and it should sound like bacon sizzling in a frying pan while welding.
Remember, voltage=penetration and wire speed=amperage or heat.
Too much wire speed, and the wire will tend to stub and push the gun away from the weld, and too much voltage will make the wire burn back to the tip.
This is how I was taught to do it, and I have several welding tickets in stick, mig, flux core, and tig welding.
And don't forget, the cleaner the metal is, the better and more consistent your welds will be especially with mig or tig.
I hope this helps..........