What kind of iron do you have? I use a no-steam iron (with aluminum soleplate).
When the iron gets dirty I use an SOS pad to clean with a bit of water.
To avoid the mess, I don't cook the starch. I make a starch slurry then add boiling
water. After starching my fabric, I let it rest in the fridge overnight. Then wrap
in towels to dry until slightly damp. Then take to my ironing board. I use a silicone
sheet over the fabric until it's 99% dry. My iron stays clean.