Assuming that you have good reasons for keeping an online diary, there are a few things you can do to improve your chances of making your diary readable. I’ll begin by stating the general principles, and then by reviewing a few breakable rules of thumb that, in my experience, are good indicators of an interesting diary.
The general principle of good writing is to determine your audience, and write for them. An online diarist will normally encounter some tension here — the diarists are often writing partly for themselves or their future selves, and the desire to record events that were important to them may conflict with the desire to record events in an interesting way. You will need to decide to what extent you are intending to resolve this tension in the audience’s favour.
It is the case, if I am part of your audience, that your choice of material is generally meaningless to me, and the use to which you put your material is everything, which is why most of these tips tend towards the stylistic.
Tell a story
Of the beginning, middle and end structure, online diarists struggle most with the ending, often because they don’t know it yet. The most successful stories are often trivial anecdotes. However, there may be an ongoing story that you don’t want to record only in hindsight. In this case, you will want to return to it periodically.
It is very very hard to make a story out of emotions you are still experiencing, unless you’re a brutally honest and particularly insightful person, so if you want to write a powerful emotional entry, you may be better off writing an entry that looks back a year or more.
Write long entries
A long diary entry gives you the chance to tell a story, rather than writing an instant message to your readership, and most good online diaries contain at least the odd long entry scattered in their archives.
Very few online diarists seem to be poets, and so generally very few short entries will not become the highlights of your diary.
Drama is the biggest online diary cliche
If your entry is an allusion to misery that only your three best friends in the world can comprehend, your entry will be boring. The high points of an online diary are very seldom the most dramatic entries, save in the case of diaries that resemble an emotional car crash. For the rest, you will need to hone your ability to make the prosaic interesting, because it is actually much easier to do that than to make secretive drama interesting.
Make your entries complete within themselves
Again, if your entry is full of allusions to events you cannot describe in full, and people you cannot say anything about, and feelings that you are unwilling to share, your entry will be boring. If you need to censor something that is crucial to understanding a story, you may as well censor the entire story. In other cases, tell the story in such a way that it is a complete anecdote, even if it is not totally uncensored. If your reader can tell that you’ve left part of the story out, your entry is not as good as it could be.
A subtle style will serve you well
A diary with a unique voice is often an interesting read. One of the easiest ways to achieve this is to let your spoken style influence your written style. It should be relatively sparing, but a touch of spoken mannerisms in a diary makes it more readable.