It depends on the country you are in, if possible try to buy from a vendor in your country. International packages are much more heavily scrutinized than regular mail. As far as extracting take meticulous notes, photos, and THROW NOTHING AWAY, just in case.
Legality wise, few have had any issue from ordering the supplies. Avoid eBay and Amazon ordering mimosa, naptha, and lye at the same time is just foolish. Try to obtain things that are locally sourced. Be patient. If in doubt ask and wait for a response. Easier to take 10 days than it is to undo a mistake or wait a month for new supplies. Another basic tip is to only use half of your mimosa. It's the all the eggs in one basket philosophy, If you blow your extraction you still have another run. And in the end, stick to the guide, they wouldn't be here if they didn't work. 90% of the fails in a run are a result of improvising. Your welcome to do it your own way just wait until you have it down before messing with the variables.
If you don't sin, Jesus died for nothing.