What about gestures? Do I have to practice those too in front of the mirror. I figured there mght be hand exercises so that my hands will be less tense. Thanks!
Yes, absolutely, but practice them in context.
First, next time you go speak with someone, or do a presentation, make a note of what gestures come naturally to you. For example, I like to walk around in a presentation and gesture in a wave with my right hand. I also tend to sometimes avoid eye contact when I'm thinking too hard about my presentation.
Once you know what you do, you can work on a) making it look better and b) eliminating gestures that don't look like you. In this way you can streamline how you use your body in performance and feel more at ease with yourself.
As far as hand exercises, yes, there are quite a number of dexterity exercises around. XB has some as well, from memory.