All opinions my own. Be aware that the fibers for fine hand-knitting yarns may require special care - "real" wool will shrink and felt, acrylic will soften and loose its finish, polyester yarn can "melt" in the dryer. A cast-on that is not too loose and not too tight is critical to the project and can't be fixed after the project is started (you will have to rip out to fix). Same with the starting chain for a crochet project. A bound-off edge (ending edge) that is too tight or too loose can usually be fixed by un-knitting and re-knitting the edge. It's better to fix any mistake as soon as you see it than to keep going and try to fix it later. Sometimes a dropped stitch in knitting can be fixed with a crochet hook, and the fix won't show after blocking. When knitting, weaving in ends is better done after the whole item is finished - and weaving in ends along the side edges creates bulk that can interfere with seaming or edgin
