I would take this one step further and say eliminate the word 'try' completely. It weakens the request. You can ask a young child to try not to spill a glass of milk, but asking a gun-wielding adult to try not to shoot any more bears is a bit demeaning to the adult if you think about it. Or worse, it implies your understanding (and by extension, your approval) of the fact that they might actually 'accidentally' shoot more bears. ;-)
Taken from a dictinary published 1958: 'jitter' v.i. Colloq. to talk or act nervously [variant of 'chitter'] 'chitter' Scot. to shiver, as with cold [var of 'chatter'] (as in when your teeth are chattering).
To have the jitters denotes fear, yes, but mostly in the sense of some nervousness or anxiety being the cause, not fear in the sense of fright or terror.
A simple thing to help remember: insert the word 'expected' or 'allowed' between the 'be' verb (no matter what tense) and 'to', for example, 'to be (expected) to' or 'to be allowed to". If you go back through all the sentences Joe posted and insert the word 'expected' or 'allowed' (as context dictates), you'll see they make more sense.
The nurses took care of the patient but he was (expected) to die by the end of the night. Obama is (expected) to make a speech tomorrow. As agreed, I am (expected) to tell the truth. According to the law I am not (allowed) to kill my neighbour. Dogs are not (allowed) to run in the park.
'Dates' are not just romantic or intimate in nature. Saying 'lunch date' to describe a casual meeting with a client or business partner over a meal is just as acceptable as calling a pre-organized gathering of young children a 'play date'.