I try to do as many of my own repairs on my bike as possible. A real mechanic at a bike shop can do it way better than I can do it myself, but I’m trying to get better. One thing I’ve realized is that having the right tool for a job is pretty important. A lot of the work on your bike CAN be done with a multitool, but having "real" tools usually makes the job easier.
When it comes to cutting cables and cable housings, a good pair of cable cutters is a must.
I picked up these Jagwire cable cutters from Schlegel's a few months ago. I think it was Daniel and Marty that recommended them; maybe it was also Joey. The price was super affordable. They work so great that I couldn't imagine wanting to spend more for anything else. These things are awesome.
They are super sharp and have lots of leverage. They go right through the inner wires and housings. Shift cable housing and brake cable housing are equally as easy. The first time I tried to do this job myself I assumed that my Craftsman (or something like that) dikes would be just fine. They weren't. They are like butter knives compared to these.
I've mentioned before that I really like functionality, and tools with multiple purposes. These cutters have a few "hidden" features to them. They have built in crimpers for the end caps that you crimp onto the cables. They also have an awl built into one of the handles. You poke the awl through the cable housing in order to round the housing back out and eliminate friction on the inner wire.