Because I never get exactly the same materials as recommended in a pattern and more often than not, I am often creating crochet stuff with whatever yarns and threads (and beads) I have on hand, I have found that not listening to my rule of thumb has always been to my detriment and to my project at hand.
So the rule of thumb is (given whatever size yarn and/or beads you are using):
- If the hook constantly catches (and often splits your yarn) - then your hook is too small.
- If you find difficulty in pushing into a previous row's stitch (to make your current stitch) - then your hook is too large.
That's it. Short and simple. Now, if only I would be consistent in listening to myself, that would be great!