Assuming you are in possession of an ATPL 4 stripes would be fine, 3 stripes for a CPL and I think 2 stripes for PPL (I am not sure about this one), at least that is what cadet's are allowed to wear, once they have gone past the PPL stage.
It is true, that in certain countries at certain airports proper uniform with bars do help proceedings, but be carefull: If you rock up with 4 stripes without a crew ID card, you might be asked for your licence. If that is a PPL, the benefit you were hoping for may be gone very quickly!