I would hesitate before blackening your sights.
I shot in an indoor league when I was in college, and a guy from the Navy who was pretty good offered to blacken the front sight on my S&W Model 29. Yup! it was (and is) a 44 Magnum, but I was using lighter loads than the 45 guys and that Model 29 with the 8.375" barrel weighs a lot.
He used a carbide lantern to blacken the front sight. This turned out to be a mistake, because he melted and carbonized the red plastic insert on the front sight! It did not affect the accuracy but the appearance was hit.
The pistol has seen a lot of use since then and shows a fair bit of wear, so 40 years later I don't feel so hurt.
I have also shot pistols with the three-dot sights. You can ignore the dots and line up the sights the conventional way, so blackening them may not be necessary. You will likely go to formal target sights in a year or two when the competition bug really bites you anyway!
Similarly, filing the sights mean that they will no longer be what they were. One should be sure of what he wants or needs before doing that.
Before filing those sights, I recommend you first concentrate on shooting good groups. What do I mean by good groups? Any group small enough to be covered by the 25 yard slow-fire bullseye is a good group. Get the group to be good enough before even attempting to center it on target. After that, try Kentucky Windage and Tennessee Elevation to move the group closer to target. Only then are you ready to make adjustments that might be permanent changes to your sights.
In all cases, the top of the front sight needs to be precisely level with the top of the rear sight. There should be an equal amount of light showing between the blade and the sides of the notch. For all practical purposes, this alignment is more important than where the pistol is actually pointed on the target.
Some folks like to shoot these competitions using a center-hold. A center hold has the top of the sights aligned with the center of the target. This hold might be good enough to get a good group.
The best hold I've seen, and I use it exclusively even in my informal pistol shooting, is the six O'Clock hold. In this one, I imagine resting the bullseye on top of the precisely aligned sights.
Why do I like this hold better? This hold gives more precise aiming references. The thinning whitespace as you see the bottom of the black circle helps get precise vertial alignment because you want the space to drop to a consistently narrow thickness. For me, it's about a quarter to half-inch at 25 yards. Further, being able to see the bottom of the bull lets you center it on top of the blade.
What's the difference in precision? For me in the '60s and '70s, I could fairly easily get all the shots in the 8-ring with the center hold. The Six O'clock hold meant I could get more than 90 shots out of 100 inside the 9 ring, with the occasional score of 100 for ten shots. I could also get one hole 5-shot groups about one in every five or so groups. Getting a 10-X was more challenging because the group also has to be precisely centered. I don't remember getting one but was otherwise reasonably competitive.