Hi, Can anyone help?

Excited to get started printing some canvas bags but no instructions included with my heat press.. I've had a go, but prints are coming out pale..

I've been pressing at 180 for 45 seconds... (was just a guess from other websites)

Also, should I be placing anything inbetween my bags when pressing, and do I need protective paper underneath or on top of the bag..

Sorry if these are blonde questions.. but then again I am! LOL

Thanks in advance... but please hurry as sooooo excited!