…is very simple. Buy and install a SSD (Solid State Disk) in your laptop.
I spent the last year with a fairly high end Macbook Pro, and yet I found myself constantly waiting for it to load things or respond to commands. Over the last twenty years, we’ve learned to think that whether a computer is “slow” and “fast” depends on the CPU. These days, that’s hardly ever true – your CPU is plenty fast and instead you spend time waiting for your hard drive to physically spin a little disk into position.
Switch to an SSD and that wait time almost completely disappears. Subjectively speaking, the time to boot my laptop has dropped by 70%, and the time to open Chrome (and the 15 or so tabs I usually have open) has dropped from about 3 minutes down to 15 seconds.
SSD’s are rapidly getting cheaper. Although they still have limited space, if you have an optical drive in your laptop you can usually move the current hard drive to where the mostly useless DVD drive currently is, use the old hard-drive for stuff like movies and music, and overall still have plenty of space.
I bought a 240GB drive from OWC, who has excellent instructional videos for how to do the install.
Just do it. It will immediately make your life better.