I wouldn't necessarily say you need LyX for quick writing of documents/note-taking (it's more to ease the learning curve), but the following method should work well with either plain LaTeX or LyX I believe.
At present there exist the excellent babel and hebfont packages. The combination of these two packages is likely the best option for typesetting Hebrew text. The former provides support for Hebrew characters/text encoding, RTL rendering, and switching between Hebrew/Latin/other scripts, while the latter provides a variety of fonts for rendering Hebrew characters.
You can turn 'Hebrew mode' on simply with the \sethebrew macro, and off again with the \unsethebrew macro.
Boris Lavva has written a very useful guide to typesetting Hebrew in LaTex 2e, which should get you going. It would probably be fairly straightforward to set up a template for Hebrew documents. Apart from a handful of new macros to learn, you should essentially be able to use Hebrew in LaTeX as you would normal LaTeX.
Note: There is even a hebtech document class for preparing formal technical documents/theses in Hebrew, if you find the need.