In Hamlet II.ii, Hamlet muses on how one of the actor shows great depth in his emotional engagement with the play. With the famous line, "What's Hecuba to him, or he to Hecuba / That he should weep for her?", Hamlet marvels at the way the actor seems to care about a character/historical person whom he has never met, while Hamlet has difficulty engaging with his own emotions about his father's death and seeking revenge against Claudius.
In HamletIII.ii, Hamlet gives lots of specific advice to the actors.
+ "Speak the speech, I pray you, as I pronounc'd it to you, trippingly on the tongue" (Perform the speech smoothly, the way I showed you)
-"Nor do not saw the air too much with your hand, thus, but use all gently" (Don't use a lot of wild hand gestures)
+ "In the very torrent, tempest, and as I may say, whirlwind of your passion, you must acquire and beget a temperance that may give it smoothness" (even when you act strong feelings on stage, balance it with smooth calmness)
- "O, it offends me to the soul to hear a robustious periwig-pated fellow tear a passion to totters, to very rags, to spleet the ears of the groundlings, who for the most part are capable of nothing but inexplicable dumb shows and noise" (I hate hearing actors, wearing ridiculous wigs, who shout and over-act on stage for the benefit of the lowest-paying audience members, who can only appreciate shouting and pantomime shows)
-"I would have such a fellow whipt for o'erdoing Termagant, it out-Herods Herod, pray you avoid it" (I would whip an over-acting actor; don't overact)
-"Be not too tame neither" (Don't under-act, either)
+"but let your own discretion be your tutor" (Use good judgment to guide your action)
+"Suit the action to the word, the word to the action, with this special observance, that you o'erstep not the modesty of nature: for any thing so o'erdone is from the purpose of playing, whose end, both at the first and now, was and is, to hold as 'twere the mirror up to nature" (Balance the speaking and acting. Do not exaggerate. The purpose of acting is to show reality.)
+"Now this overdone, or come tardy off, though it makes the un-skillful laugh, cannot but make the judicious grieve; the censure of which one must in your allowance o'erweigh a whole theatre of others." (If you exaggerate or act badly, you will entertain ignorant people but make people with good judgment unhappy, and intelligent people are the most important part of the audience)
-"Oh, there be players that I have seen play--and heard others [praise] (and that highly)--not to speak it profanely, that, neither having th' accent of Christians nor the gait of Christian, pagan, nor man, have so strutted and bellowed that I have thought some of nature’s journeymen had made men and not made them well, they imitated humanity so abominably." (I have seen some actors with good reputations who can't even walk and talk like a real person on stage)
+"And let those that play your clowns speak no more than is set down for them, for there be of them that will themselves laugh to set on some quantity of barren spectators to laugh too, though in the meantime some necessary question of the play be then to be considered" (Make sure your comedy actors don't selfishly make up extra lines. Some of the audience might laugh at extra jokes, but important parts of the plot might be missing if the comedians re-write lines)