The above video depicts how to increase evenly with one stitch on either side of the work. Do as follows:

Step One - Insert hook into top horizontal bar between edge and 1st inside vertical bar.

Step Two - Yarn over and pull up a loop. One increase made.

Step Three - Work remaining stitches, with the except of the edge stitch, per usual.

Step Four - Insert hook into top horizontal bar between 2nd to last vertical bar and the end-edge loop.

Step Five - Yarn over and pull up a loop. One increase made.

Step Six - Complete forward pass by inserting hook into the end-edge loop, and the back loop behind it.

Step Seven - Yarn over and pull up a loop. Forward pass increase row complete.