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If you're asking, "should I keep a diary and hope that it is useful for future historians" — I mean, knock yourself out. On an individual level that doesn't usually help much, but feel free to go ahead. You never know, and if it makes you feel good doing it, then do it for that purpose.

If you do, at some date (now or later), end up being in control of records that you think might have historical value (whether they be personal, familial, corporate, governmental, etc.), by all means, look into ways to secure them for future researchers (e.g., donations to archives or libraries). You never know what a future historian will find fascinating, and it is all too frustrating to learn that some major corporation decided to just purge its records rather than to keep them visible for posterity.

But if you're asking, is there some way I can, as a non-historian/non-archivist/non-someone-already-connected-to-this-field, directly contribute to historical research... it's not that easy, usually. There are ways in which "amateurs" help, but usually that involves becoming some kind of specialist expert yourself. (E.g., I found the resources of the Pullman Porter Train amateur community very useful for a paper I wrote once.) I don't think one should pursue such things with the goal of helping historians — pursue them because you like to do them, and if it turns out to be helpful to a historian down the line, well, good for them and good for you.