Anyone who has ever done any simple sound editing or mixing of any kind with their computer will have, at some point, encountered or even used an open-source program called Audacity. It is probably one of the better programs of that type available, though my use of it was sporadic and basic prior to getting engaged.
As implied, since getting engaged, my familiarity and skill with using Audacity has increased significantly. I hesitate to call myself an expert, but I'm definitely adept enough at it that I know roughly how to get it to do what I need it to do.
This, I think, was a natural result of having 2 people who disagree on what makes "good music". This wasn't such a big issue with the reception, where our music selections could take turns to feature, but it started to become one with the ceremony. I really wanted us both to like what was going to play for the ceremony.
Fortunately, while we had deeply divergent tastes in music, we did have strikingly similar tastes in movies. The problem with using music from movies, however, is that just because you like it doesn't mean it's always suitable for the occasion. It'd been chosen in that movie to reflect/support/heighten a particular scene or event on-screen, and if our guests haven't seen the movie in question, hearing the music alone means they may miss out on a big part of the experience.
That meant that any movie music we decided to use was rarely appropriate as it stood. There were certainly cases where the music was suitable in its original and unedited form (usually because the movie was popular enough or the message was pretty obvious even context-free), but these were few and far between.
Thus came the search for more suitable versions of the music we wanted to use or reference. Acoustic only, for example. Or a slower cover. Or instrumentals only. And it was surprisingly hard to find precisely what we wanted. Youtube was a great source, but depending on the piece of music I was after, there were either only a handful of options or an overwhelming number to filter through. It got stressful pretty fast, particularly when you consider that it's not just my opinion on a cover that matters - Blake's does, too!
I should clarify that we weren't picky to the point where we were going to record anything ourselves. I was happy enough to jury-rig songs to get them to sound roughly like what I'd envisioned. That's where Audacity came in.
The best thing about open-source, popular software like Audacity is that tutorials and how-to's abound on the internet. If I ever wasn't sure how to get a piece of music to do something, a quick Google search would solve my problem. Use it enough times and you start to figure out what the other "bits" of the software are there to do, and some hilarious experimentation eventually did get me feeling pretty comfortable with it.
None of it's perfect, necessarily, but it'll suit.