How to get straight edges when crocheting
In this DROPS video we show how to avoid getting a wavy edge and small gaps in the edges. We often use 3 chain stitches at the beginning of each row when working treble crochet back and forth to get the same height as a treble crochet. These chain stitch can either be in addition to the treble crochets on the row (this creates extra stitches and the edge becomes wavy) or the chain stitches counts as a treble crochet (this will create a hole on every other row).
This can be avoided by pulling out the 1st stitch on the row, holding this stitch firmly with your finger, moving the hook towards you and then under the long first stitch, insert the needle into the first stitch (on the 1st row work the needle under 2 threads), get the thread and work a regular treble crochet. This stitch will be slightly loose, but on the next row it will be fine. Work like this in every row.
We use the yarn DROPS Snow in this video.