I think the rules are in many ways similar to that of setting Latin text, though without the options of emphasis we have, and in reverse. Also note that Hebrew has a different system of harmony than Latin. If Hebrew is on the same line as Latin, the two languages should be sized so that the Hebrew mem-height is somewhere inbetween the Latin x- and cap-heights. Hebrew line-heights are going to be different than Latin, so try to make it balanced and have enough space between the lines and be careful with the measure.

Your best bet might be to look at Hebrew books and see how they are set. Might help:

1. The Hebrew book : An historical survey. (1975)
   A survey of Hebrew books throughout history. Depending on the feeling you're going for, you can look at an appropriate period.
2. The New Hebrew Typography (1932)
3. Hebrew Typography, a website that has a PDF download.
4. Ari Davidow's website on Hebrew typesetting
   Ignore the unsubtle website design. Ari is not a web developer. :)
5. Hebrew Typography Annotated Bibliography

Alright, forget #2. Sorry, I had forgotten the title of that work. I found the book on Worldcat when searching for 'Hebrew Typography'—the name of the work sounds nice... I do own a copy of #1 and quite enjoy looking at it.

do you happen to know when?