...there's no point in choosing a F-A-B-U-L-O-U-S style, then spending your precious time and skills making a great garment if you don't use a suitable fabric! this doesn't mean that you *must* stay with the fabrics recommended on your pattern envelope, but you *should* choose something that will work with your chosen style...

...for instance, if you are making a flowy, drapey skirt-the pattern envelope might say, use silk charmeuse or chiffon...you may want to use, for instance, a single knit. well, as long as your chosen fabric has the same or a similar feel or handle to the suggested fabrics, you're pretty much good to go...

...but if you were to make up that same flowy, drapey skirt in something like, for instance, a firm denim-well, you may still get a fabulous garment, but it won't look like the original design...and that's ok, just be aware that deviating from the suggested fabrics may *not* give you the look you want...