So far, I have told you a brick wall is not a proper filing implement and filing after you have pruned yourself in the bathtub is also a bad idea. I want to do a series of posts for successful filing of "normal healthy nails." This is the first of that set. This post will specifically cover how to take down nail length, specific nail shapes are covered here, while sealing the nail plate is covered here.
What do I consider a "normal healthy nail?" It's when you DON'T have flaking, peeling, or tearing. How to handle/file an occasional peel is covered in this post. How to handle breaks or tears, especially on the side of the nail wall are covered in this post.
There are several ways to take down nail length. If you have significant growth (>1cm) I would recommend nice sharp clippers: otherwise, follow the steps below.
1. It is best to start filing nails when they are in a normal dry state WITH polish on. If you just took a shower/bath, did the dishes, or soaked your nails from a regular mani (which I don't recommend, more on that in this post*link*), apply moisturizer and let them dry thoroughly. Leaving polish on your nails while filing will prevent and protect the nail from shredding or ripping due to over zealous filing (see #2). Additionally, if you are wearing a dark color your nail shape is much more visible, thus easier to shape. However, some filing will also be done after polish removal, particularly to seal the nail plate.
If you already took polish off or it's been off, apply some moisturizer anyway, its good for you!
2. Since this post is concentrating on taking down nail length, we first need to choose the correct file for the job. See the older post on types of files, grit and uses. Determine whether your nail is thick or thin. Thick nails can use a 220 grit file, while thin nails are a bit more fragile and should start with a 300 grit file or higher. Perhaps a crystal nail file would work for thin nails, but as I said previously, I am not that big of a fan.
Nail filing should, for the most part, be done in one direction and not in a sawing motion. The exception is using a higher grit file (400+). Grit this high is safe and will not tear the nail even if you are sawing away. I can't comment too confidently on glass nail files, but from what I have read they seem to be safe.
Since you are not refining the nail shape, only keep a nail shape in mind. Then file in one direction until your achieve length is achieved. Or you can choose a higher grit nail file and saw away! Maybe a video would be helpful. If enough people express interest I will add one.
Now that you have taken down the length we can refine the shape!
Not sure what the right shape is for you fingers. See this post!