Sometimes I journal on my clipboard and put it in a 3-ring binder; if you are in school, you could intersperse pages in a/notebook(s) used for school so no one would be curious? Code the dates or something so only you know what it really is (so it doesn't look sequential).

I would also maybe fold pages in half and put them in the back of uninteresting books or other hiding places. I know I ended up with a lot of journals at one point and read through them and consolidated the "best" information I wanted to keep into a "new" journal and then destroyed the old ones. Over the years there is a lot of repetition and not "important" or interesting stuff?