In addition to checking Ulrich's and the A to Z Journal Directory, also consult what the professional associations in your field are. Most of them also have journals or other publications associated with membership.
One way to find the associations in your field is to go to the Bureau of Labor Statistics' Occupational Outlook Handbook. Find your profession and read about the career trends. Click the tab that says "More Info" and a list of associations with web sites will appear.
Here is a useful guide to determining the difference between a scholarly, trade, or popular periodical:
Don't forget -- The database UlrichsWeb allows you to determine the readership and type of any print or online periodical. It will let you know if the periodical is a trade, popular, or peer-reviewed scholarly source.