When most people think of crochet, they think of granny squares or doilies. The same techniques may be used in both, but there is a different skill set for each. From reviewing most of my crochet work, I usually play with yarn, and thus take it for granted, but picking up some thread can easily bring all the technique needed to crochet into focus for me.
It is not that yarn and thread crochet have that many differences, they use a hook, they have the same stitches and they are creating a series of knots, but where the differences come into play is the execution of those stitches. In yarn I automatically adjust my tension dependent upon the yarn weight and fiber type (some silky yarns tend to slide a bit), but nothing in the yarn realm can prepare me for tensioning thread.
Tension can definitely affect the appearance of your work, more than first realized. Some tensions are too tight and stitches are tight and compact compared to a tension that is too loose, resulting in stitches that appear sloppy. Too tight/loose tension can make it appear that you are using the incorrect hook size, but it doesn’t really improving after you adjust your hook.
I usually keep a fairly loose tension, thus I pull the yarn out of the skein and then begin to crochet, but with thread this is far too loose for me, and I have to weave it through my fingers differently in order to get control of it. I usually don’t wrap yarn around my fingers but weave it between them, thread I wrap around a finger to increase my tension and thus improve my stitches.
Even adjusting for my tension, there is a factor within thread crochet that varies greatly from yarn. Thread is less forgiving. Often in yarn projects mistakes are masked by the yarn, but in thread every aspect of your work is seen. The direction that you pull up you yarn-overs (YO) is even noticeable in thread crochet, so you have to pay attention to your work. It is a medium that I practice in, so that I can have some presentable thread work.
If you haven’t had success with using thread, play with it and see if adjusting your tension and paying attention to your stitches help, and appreciate the work of those that have mastered these skills. Those small dainty stitches are the work of disciplined techniques.