I think that SanDisk SSD is a good product. It certainly has been reliable over the past 8+ years. I'm sure that these days, there are faster SSDs out there, but you need to confirm that you MBP model has the appropriate SATA speeds to interoperate.
I googled a guide on how to replace disk drives and since it was a long time ago I can't remember the exact steps. But it was roughly as follows:
Put SSD into a USB HD case.
Clone internal disk onto new SSD, the tool allowed the use of larger drive. Again, can't remember the exact program. It was recommended by the guide I followed.
Make a TimeMachine backup - you know, just in case something goes bad.
Shut down MBP
Remove screws on bottom
Locate HD, remove, move some mounting hardware onto SSD (now out of USB case)
Screw in SSD and connect cables - power and SATA.
Put bottom back on, replacing screws. NB: some are longer than others so you need to keep track of which ones go where. Again the reference guide had good hints.
Power up MBP, activate Trim program.
Enjoy.
