Google search tips are provided in one of my earlier posts.

Following are some search tips for Gmail messages.

Searching based on E-Mail Headers:

a) use to:{emailid} or to:{contactname} for searching emails that you sent for a specific person.
Ex: to:jacob@gmail.com or to:chetan
b) use from:{emailid} or from:{contactname} for searching emails that are from a specific person.
Ex: from:sjoe@yahoo.com or from:San
c) use subject:{text} for searching emails which has subject
Ex: subject:resume
will list out all emails which have subject resume.
Similarly you can search for bcc: or cc:

Searching for Attachments:

a) use has:attachment , to search all email messages which have attachments attached to them.
b) use filename:doc , to search for email messages with attachments and the attachment file name contains doc.
c) you can combine both searches.
Ex: has:attachment filename:pdf

Searching based on Date:

Searching based on date requires you to put date format in yyyy/mm/dd
a) after:2009/02/09 will search for all emails after 09 Feb 2009, but not on the date.
b) before:2009/02/09 will search for all emails that came before 09 Feb 2009, but not on the date.

Boolean operators can also be used while searching in Gmail.
Ex: to:Dany subject:(stocks|news)
above search query searches for emails which are sent to Dany and with subject messages either stocks or news.

Gmail searching by default excludes Trash and Spam messages, if you want to include these folders, use in:anywhere with your search query.
Ex: from:Dany in:anywhere