Firstly, there are plenty of guides to team talks that are all very detailed an in-depth, this is a brief guide to pre-match team talks.
Secondly, as team talks can be one of the most troublesome aspects of FM11 I've decided to post a bit of help.
You Can Win: I use this for any match that I'm not a clear favourite in; it seems to instil a bit of self-belief.
Wish Luck: I only use this when morale is really low, for some reason it seems to raise morale, therefore giving you a better chance of a result.
Expect to win: This is one I use rarely, for some reason it doesn't seem to work with me, but if you want to use it, I suggest only using it in the home matches against the poorest of sides to try and prevent complacency.
For the Fans: This is often used when playing rivals, I also use it when playing certain away games.
No Pressure: I'm still a bit unsure as to the use of this one, as nearly every football match has some level of pressure involved, even when you're a non-league side away to Chelsea in the cup.
Please post any personal experience you've had with team talks below.