Suggestions to make a old Macbook Pro faster?
I put a 260 GB Intel 530 Series SSD into my mid-2009 MacBook Pro and it did wonders for it, cut the boot-up time in half. Just get a good brand, my Intel hasn't had any problems

You could also upgrade the RAM. Other World Computing is a great place to buy RAM for your specific model of Mac.

My Mid-2009 MacBook Pro runs El Capitan pretty well, so you may as well update to it, as El Capitan is supposed to make Macs (even older models) run faster. That's my experience with El Capitan, but YMMV.

An SSD, RAM, and El Capitan is where I would start if I wanted to upgrade any Mac.