Learn how Peter Vogl starts out his classical guitar practice each day. This is a great tip for dialing in your tone.
Try playing the guitar with your nail striking the strings at a variety of angles. Once you discover a tone that you like, you should repeat the motion and lock in on it. That will be your core tone for the day. From there, you can experiment with other angles that you might want to use to create different tones. You should repeat this process for each finger. Every day your nails are a little bit different so you are going to have to adjust to get the sound your want. This process is a good place to start the day and gain confidence heading into a practice session or performance.