Holding tightly to them refers to being committed to obeying them. AT: "I hold tightly to your covenant decrees" or "I am committed to obeying your covenant decrees" (See: [[rc://en/ta/man/translate/figs-metaphor]])
The writer speaks of being focused or committed to obeying God's commands as if one is running on a path. AT: "I will be committed to obey your commands" (See: [[rc://en/ta/man/translate/figs-metaphor]])
This is an idiom. Possible meanings are 1) "you help me gain greater understanding of your commands" or 2) "you give me greater desire to obey your commands" (See: [[rc://en/ta/man/translate/figs-idiom]])