What are the guidelines that should be followed to adhere to prayer and sincere repentance, taking into account the feeling of constant regret and irregular performance of acts of worship?

Your negligence in prayer and abandoning it is a grave sin, and your regret over sins is a good thing; indeed, regret is repentance.

You should invest this regret in performing good deeds and drawing closer to Allah through acts of obedience, the foremost of which is seeking religious knowledge.

Rectify what you have missed due to negligence, have a good opinion of your Lord, and strive in seeking forgiveness, remembrance of Allah, and all other acts of obedience.

Commit to making up for the prayers you missed, and the burden you feel from worship will dissipate with perseverance, for perseverance makes the soul compliant in performing acts of obedience.