At your level, that is kind of subjective.
You should ask what your teacher wants/they should give you a guide line. As so much of the stuff/style you use in your early chemistry academic career is just to make it easier for the instructor to grade, while checking to see if you understood what is going one.
The two main things, pick a verb tense and stick with it (either past or present tense, do not switch around). And make sure to check your significant figures!
But really, I would ask your instructor for a general outline.