Ask most about the proper way to trim a toenail and the answer is likely to be "straight across." Following that advice would generally keep you out of trouble. When people cut their toenails, especially if they are feeling pain from a nail starting to grow in, they tend to angle the sides. This is asking for a problem. When a toenail begins to dig in to the toe, it occurs at a deep level where you aren't able to easily reach without causing yourself pain.  

Most ingrown toenails are not caused from cutting the nails wrong, however.  They are made worse when you try to perform your own ingrown toenail surgery.  The ingrown toenail typically occurs when the toenail is too wide for the nail bed. It's simply the way you were made, nothing you can do to change it.  If you notice a redness, bulging, or pain on the sides of your toenails, your best bet is to visit your Houston podiatrist to have it evaluated and properly treated.