If any co-authors, you need to use we since we don't know who the I is.

Use I, as needed. I like I because it is a strong statement--there is a definite person to hold responsible. Don't use "we" if there are no co-authors (what you got a mouse in your pocket?)

Do not use I when it makes more sense to make the objects of the research, the subject of the sentences. For example NOT "I observed pitching as the stall angle was approached", but "the model started pitching near the listed stall angle, about 35 degrees". The reason is not for modesty but because (a) it is tighter writing and (b) the proper attention is on the model in the wind tunnel--your observation is not the point, here.

I recommend to avoid the passive voice, but some people will recommend it or expect it. Certainly if an editor requires it, just do it, don't argue. "The reactants were combined in a boiling flask..." Note, it does have the benefit of putting the attention on the science, not on you as an actor.

Some math writing uses we because the reader is included as an observer in a derivation, "after completing the square, we see...blabla".

If any co-authors, you need to use we since the readers don't know who the I is.

Use I, as needed for sole author pubs. I like I because it is a strong statement--there is a definite person to hold responsible. Don't use "we" if there are no co-authors (what you got a mouse in your pocket?) If you feel too hesitant about a bold I (or get static) than go to passive voice. But a "we" for a sole article is distracting.

Do not use I when it makes more sense to make the objects of the research, the subject of the sentences. For example NOT "I observed pitching as the stall angle was approached", but "the model started pitching near the listed stall angle, about 35 degrees". The reason is not for modesty but because (a) it is tighter writing and (b) the proper attention is on the model in the wind tunnel--your observation is not the point, here.

I recommend to avoid the passive voice, but some people will recommend it or expect it. Certainly if an editor requires it, just do it, don't argue. "The reactants were combined in a boiling flask..." Note, it does have the benefit of putting the attention on the science, not on you as an actor.

Some math writing uses we because the reader is included as an observer in a derivation, "after completing the square, we see...blabla".