Here is a close up picture showing the “squish” of the first layer outer ring with PLA. I use 3M Scotch Original blue tape wiped down with Alcohol Prep Pads. Most prints will bring up the tape when the print is removed.
I use printer paper as a gauge for the first layer (~.1mm). For PLA and heated bed, I have been using a bed temperature of 45C. It also works on a cold bed, but it helps removal a little when it cools down. Any hotter and the first layers stay too soft and affects the print quality.