Anyone know how to make it so an image only has one thing in color? Like entire image will be in black and white except for a persons lips or something?

I know it can be done with layers, and masks, but it's really hard (for me) to do it this way when it comes to the detail

just go into mask mode... take ur black paintbrush... and color everything u want to stay in color... (it will appear like ur making it red but once u get out of mask mode it will look like the original)
then get out of mask mode and u will have everything else selected...
image >> adjustments >> black and white..

now everything is black and white cept for the things u wanted to stay in color...