I am relatively new to yoyoing (I’ve done it for years, but haven’t paid much attention and care to it until now. I used to use a fixed axle but now I use a sage) but I noticed that when I go into a front mount, it starts to lean to the side which kills the spin pretty fast.
Adam is in a front mount but his yoyo string hand was way off to the side but it didn’t kill the spin. Does anyone else have this problem? Does anyone know of a solution?
That’s very normal at the beggining. Eventually you develop the dexterity to make small compensations kind of like driving a car and making those small adjustments on your steering wheel.
I wish I had a better way to tell you or explain it. I almost want to say one of the beginner tutorials on yo tricks describes this exact thing but I cant recall which video
For me it’s tilt in every mount
I learned front mount from this video and I just put my phone down to do a bunch of front mounts on a responsive Sage. Keep your non throw hand directly in front of you (centered perfectly) and your non throw hand index finger perfectly parallel to your body. The center of the yoyo should be pointing straight ahead. Doing this with a good solid and straight throw allows you some freedom with your throw hand - like having it over to the right a bit like Adam does in the video. It just takes practice. I find with frontstyle tricks you really need to keep both your index fingers very straight / parallel to your body. From the Yonomicon:
Absolutely agree with this! 
It can be frustrating, but stick with it and you really will start getting it!
