I have been making daisies tonight with a daisy cutter, and my fondant (with mixed in tylose) keeps coming out with rough edges. I've been trying to tidy them up with a toothpick, but they don't look perfect. How can I either a) avoid it altogether, or b) fix it in a way easier than with a toothpick?

What are you cutting them on? if you are cutting them on a silicone mat you wont get a crisp cut or if your cutter is dirty (has old gumpaste built up on it) you will get uneven cutting. Roll your gumpaste out and transfer it onto your bench or something smooth and flat.

I'm doing it on a hard plastic tray, which I'd just scrubbed clean and dried thoroughly. The cutters are brand new, first time out of the box!

btw, I also tried a little bit of shortening, but that didn't work either.

I have that problem too! Somebody showed me a trick with stretching glad wrap over your paste first then using your cutter over it, to give a smoother edge. I havn't tried it yet, maybe give it a go?

Anything's worth a crack! Also I just remembered seeing a picture of someone who turned their cutters upside down, lay the fondant over them, then rolled a rolling pin over the top. I'll give that a go too.

But I really think there must be an easier way?

The following is a simple way i was shown to get clean edges on cut outs - cut out flower / shape etc, whilst fondant is still in cutter pick up cutter and turn over (so fondant is facing you), now just run your finger around the edge of the cutter, this rubs off all ragged edges of fondant. Now when you remove fondant cut out from cutter, you have a lovely clean edge! Hope these instructions are clear!

I cut, then without lifting it, I rub back and forth on my work surface.

Yep, what Emmar said. That's what we do too.