There are limitations put on your ability to request an appeal of a criminal conviction in Tennessee. One of those is that you have to have a compelling legal reason to request an appeal. One common reason is ineffective assistance of counsel, which, according to Jurist, is your assertion that your attorney did not adequately represent you in your case and that led to your conviction.
There are two criteria that your situation must meet to prove this as a ground for an appeal. First, you have to show that your attorney acted in a way that was prejudicial to the defense. Second, you have to show your attorney acted in a way that was outside the reasonable objective standard.
Essentially, if your attorney does something that harms your case and is outside of what any other attorney in that same situation would do, then you probably have a solid ground for an appeal based on ineffective assistance of counsel.
The Supreme Court even has said that this ground works after your conviction. If your attorney refuses to file an appeal for you, you may have the right to use ineffective assistance of counsel as a ground for filing.
Keep in mind that the appeals process is not a rehearing of your case. The court will not listen to witnesses or go over evidence and make a ruling about your case. The appeals court just determines if the lower court should rehear the case because something about the first case violated your rights or otherwise went against the legal standards. This information is for education and is not legal advice.