First, begin by stopping harmful action. Do the best you can, continue to reflect on your behaviors, and make improvements.
Second, help yourself, work on your ethics: honesty, sincerity, giving of time, wanting the best for everyone, enjoying the happiness of others, etc. You must do what you can do, at your own level. All this comes little by little, with work. To be just a little less egotistical, is to be a little more helpful to all those around you, is what you need right now. Just start there.
Don't worry too much about the amount of karma you have. Honestly, we all have too much. The only way is through the compassion of Christ. He will help us. We just need to put one foot in front of the other. Just do the next right thing. If you keep doing that, every day, you will improve your situation.