Ground yourself out before starting to avoid ESD.
Have another computer open to the iFixit repair guide. Read through the guide before starting. I use about three different cups to store screws in. I use one for outside screws, one for logic board connected screws and one for the other screws. I keep a Boley gauge or other Caliper Digital Caliper for measuring screws right at hand. Be very careful when disconnecting the plug ins to the logic board as they can easily pull off the logic board. Disconnect the power and battery first. Have canned air to blow out the dust. Try do it it all in one sitting, when you are fresh and can concentrate with out interruption. Ignore the phone. I put a pillow in my lap to catch any dropped screws.
Accurately measure small screws and parts. — 15 available at 19.95 each.