I've only started a few months ago but the first thing you should do if you'd like to keep track of stats is create an e-amuse account and get an e-amuse card somehow at the arcade you're gonna be going to. Mine was $6 I believe but I'm also at Round1 so I'm not sure if D&B or any other arcade would have different rates. You're gonna have to navigate Konami's website which is mostly in Japanese so good luck with that google translate is gonna be your friend for a bit.
Something I'd highly recommend starting out if you're willing to give the time is look up charts on a channel called
yuisin[MusicGame]. Their previews are pretty much always upscroll so if you're a downscroll player I found watching
O4MA pretty helpful. I liked going through videos finding charts that I think I'd either enjoy playing or test a skill that I'm not the best at.
I'm not sure how familiar you are with Cmod but DDR's charts have a lot of BPM speed-ups/slow-downs and stop gimmicks so be prepared for those, which is also why watching the chart beforehand on yuisin or o4ma (or any other channel that either plays/displays the chart) is very helpful.
Doing math to figure out the BPM you read at is also essential. I use 2.55x scroll speed on FFR and play at about 500-550 BPM scroll speed on DDR for reference. Not sure what 500 Cmod actually looks like on FFR but it feels about equivalent to me.
Hitting 9 on the keypad brings up the options menu (on white cabs and gold cabs anyway, not 100% sure about A) and the speedmod you put will multiply the display BPM and give you your scroll speed.
Ghosting to charts on the floor while you watch them is also pretty helpful for getting used to where the buttons are and the motions you're gonna be doing the entire time you play the game. Channels like
DKOYproductions are good for this with their how to execute videos. They seem to be pretty high-level charts but I've been doing it to higher level songs on like .5-.75x youtube speed for years before I actually started playing.
There's prolly a lot more but these are the things I used to get myself started up into the 14-17 range.