OK I'm no expert but I'll try my best.
1. Dont aim, float your pin in control around the area. Dont aim and try to held dead steady, thats pretty much impossible and will make you "shake". Also, make sure your form is the exact same everytime!
2. To pick the right arrow spine and all that good stuff we need specs of draw weight and length. But, I would suggest Easton or Gold Tip brand.
3. Best things hands down is some kind of STS. Maybe talk to MeanV and see what he can do for ya. Stabilizer could also help but not much compared to the STS
Hope this helps!