Based on your wording it is implied that I will get to write more than one thing, in which case:

"FunkyOne shall have all the knowledge and wisdom necessary to fully understand how this notebook works, the source of its power, and foreknowledge of any and all consequences for using it; with no irreversible, unintended, or undesirable consequences (as to be determined by FunkyOne and in effect retroactively) to be incurred for this use." Just to root out if there are any evil monkey-paw loopholes before getting in too deep.

Then "Unless and until further specified, no one else besides FunkyOne will be capable of writing in this notebook or utilizing its effects." to safeguard against the "falling into the wrong hands" cliche that always happens in these stories.

Then a set of clauses preventing or removing any similar items of power from the universe, or at least transferring them to my exclusive possession and use.

Then further clauses for added immunity from any undesired effects or consequences for use of this book (including people or other entities coming after me for having used, or attempting to acquire, or destroy this book).

Then I'd set up a whole bunch of clauses that transfer the reality warping omnipotent effects to myself via verbal commands (keyed to an activation phrase) so I don't have to keep writing every time I want something.

Then I'd probably wish for sufficient knowledge and wisdom to know what the best thing to do next is.