I have generally always used some sort of Hungarian Notation
for my field names in my tables e.g.
#Table Users
u_id, u_name, u_email etc...
#Po
I personally use lowercase for table names and pluralize. Tables such as 'people' with person records. But I got that from Rails and adopted it after time. Love it though, and this made my databases a whole lot readable. Also using so many underscores will make your databases less readable. Also I divide my database names using _ for development, test, production, alpha, beta, prototype. Once you worked with 100,000 tables or so, you'll stop writing names with too many underscores :)