My FPS Aim Trainer started out with a simple question - if I wanted a tool to grind my mechanical aiming skills, what features would I need?  This led to the design of dodging profiles that dictate how targets should move and weapon profiles to mimic guns from different games.  It all expanded out from there to become the game that is now on Steam.  

Frequently Asked Questions
The Meta (parent company of the aim trainer now) runs https://www.kovaaks.com and https://wiki.kovaaks.com/, which is going to be more up to date than the info that I have provided below.

Previously I wrote up a guide of frequently asked questions & answers - so if you are having any technical difficulties or want to know how to convert your zoom sens from a game to the aim trainer, please check it out!

Community
The community Discord server is fairly active with people providing input on hardware, sensitivity settings, aim styles, and all sorts of customization (custom crosshairs, sounds, map creation, scenario creation, etc).  Weekly competitions are run with the announcements posted in the Discord server as well as the subreddit.

Stat Tracking
A member of the community, flexxis, created a Progress Tracker Dashboard that can read the game's exported statistics and show you graphs of your progress.  For more information, see the reddit post on this tool.

Improvement guides, tips, and resources
Various members of the community have written guides on how best to use the game to improve your aim, such as:

There is great advice throughout all of the above guides.  Something I would like to add for tracking practice is the following:

  1. Play a tracking aim scenario in Free Play instead of Challenge mode. Then when you are paused, the "Session Manager" appears at the right. At the bottom of the Session Manager, there is an option to change "Timescale". 1 = full speed, 0.5 = half speed, etc.
  2. Set the Timescale down to a low value like 0.5 or 0.6, and come up with a personal goal for accuracy in your mind. As a starting example for Ascended Tracking v3, try and hit 60% (or 65%, or 70%...).
  3. Practice against the bots having the smoothest hand movements you can manage, and when the target changes directions get used to rapidly getting back on target and smoothly continuing to track without a hiccup of stopping.
  4. Once you are hitting over your target accuracy regularly, pause the game, raise timescale by 0.05 or some small amount, and press F3 to reset the statistics.
  5. Repeat 3-4 until you are back up to full speed hitting your target accuracy.

This gets you out of the habit of making constant rapid flicks to your target and results in smoother tracking aim. Being able to sustain this at full speeds is a serious improvement in your ability to control your mouse against targets in real games. It's also very similar to how you would learn a musical instrument - slow things down, get the right muscle motions happening without any excess/jittering, and then gradually speed it up to where you need to be.

If it's a flicking scenario you are trying to improve upon, I have heard of people focusing on raw speed first (flick+click over and over without worrying too much about hitting things) and getting used to what it feels like to go at your maximum speed and clicks/sec.  The important part here is to not slow down as you approach your target. After that feels pace more normal, slow it down just a little bit and try to do it more accurately, which often gives new personal bests.

My personal opinion is that if you focus on tracking scenarios with the first set of advice, you'll see more improvement in real games.