I've never really been good at comboing. The timing in older capcom and SNK fighters is so strict I could never do the more complex combos, nor try to create my own. capcom's Vs. series is too friggin' crazy for me to deal with.
But I played so much Guilty Gear that I got a pretty good handle on its combo system, and over the years was able to develop combos that worked (enough for me, anyway).
In contrast, one of my good friends is always thinking about combos when he plays fighters. He's always trying to link something new together, testing what will work. I pick stuff up as I play, but this guy is really into it.
I was trying to figure out how to better play Ragna today, and I tried a variation of a combo I had been doing. To my delight, it worked! A quick scan of Dustloop showed me that of course what I did worked, but I was doing it the stupid way for idiots with more hits but less actual damage.
Hell, it only served to remind me that I used to do Baiken's dustloop beginning with a 2k. When I was practicing the night before a tournamet, I finally figured out the 2K I thought was totally awesome was actually prorating massively and cutting the damage roughly in half.
I still don't think I'm that good with combos.