How to Shoot Wedding Photos in Low Light

Dear Jasmine,
I'm emailing you about how to shoot reception photos of the dancing. I was a second shooter for my first wedding EVER this past Saturday. It was on a yacht. When I got home and blew up all the photos in Bridge for me to analyze in detail I noticed that my weakest area of shooting is during the reception, when all of the guests are dancing. The first dance photos were totally fine, but I got maybe two good shots out of the 80-90 I took during that hour when the guests were dancing.
I tried changing the ISO on my DSLR, and toggling the f-stop to try different things and nothing was working. Obviously, I'm missing something… 

Any advice you have you may have for shooting fast paced receptions and moving, shaking, dancing people would be greatly appreciated!
Defeated by Dancing

Dear Defeated by Dancing,
Congrats on shooting your first wedding! What an amazing learning experience and I wish you the best as you follow your passion. Now let's get into the technical aspect of your question: How to Photograph Moving Subjects in Low Light.

I could get into the nitty gritty of answering this question, but when I first started, I didn't understand beefy technical responses…I wanted straight-forward tips I could apply to get better. I could learn the technicality of lighting later, I just needed to get better fast. (Sidenote: I don't think this was the best approach, but it's just how I functioned).

Here are Three Tips to Shooting Reception Photos…
    1. Bounce Your Flash
Because you were shooting on a yacht, I'm guessing the ceilings were low and the interior walls of the ship were relatively close to the dance floor. When working in this situation, I actually get excited because I can bounce (a.k.a. foof) light onto my subjects. When light is bounced from a wall behind you (this is done by turning your flash backward to face the wall, slightly tilted up), the entire wall acts as a source of reflected light. It's no longer your small flash lighting people dancing, it's the wall!
    2. Use a Second Light Source
This is my most favorite option. Leveraging off camera light in addition to the on-camera flash yields beautifully illuminated photos. This can be done in a myriad of ways, but my go-to options are: 1. using a video light (held in one hand) and the mounted flash on my camera (held in the other); or 2. using an off camera flash.
    3. Invest in Great Flash
I don't know what speedlight/flash you used, but when I first started, I used the Canon 430EX. I bought this flash because it fit into my budget…but I should've waited and invested in the Canon 580EX. I was beyond frustrated shooting with the 430EX during receptions (I'm sure it's a great flash, but it's just not powerful enough to deliver the light I needed in really dark receptions). When I finally upgraded to the 580EX a few months later (and have since upgraded to the 580EX II), I knew it was the best decision. My photos took on a new life and I started becoming happier with my end results.

I hope these tips help and the next time you shoot dancing photos, you'll be so happy with the results, you'll do a jig yourself!
Boogie On,