I agree, showing some emotion, no matter how forced, can help. Laughing, looking relaxed, talking to the people around you, etc.
Also, I wouldn't be too worried about raising your bet as much as lowering it. I see gamblers chase losses and try to get even all the time. It is not that uncommon for someone to go from $10 - $100+. But it is unusual for them to immediately go back to $10. So for me, if I have my max bets out, I leave when the shoe ends (or the count drops) so I fit the profile of someone "going all in" or trying to get even. If I am going to keep playing, I usually take a break to eat or play poker and then return to a different pit.