Contractions:
T'was, T'is, is't, e'en, o'er, ne'er, twere.
Don't use modern contractions, say both words instead.
Don't use "ain't" It wasn't developed yet.
Don't use modern Americanisms, such as Yeah, Sure, Nope, Uh-huh,
Y'know, Okay.
Never use sh for st sounds. Americans tend to tush a t followed
by a y or i sound into a ch sound so Got you becomes Gotcha.
The next hurdles is Thee/Thou versus You: English at one time
had it's formal and informal modes. The formal, used to one's
social superiors and strangers to whom one wished to be polite
was 'You'. The informal, used to one's intimates of social
inferiors was 'thou'.
"How are you?" can appropriately be said to your parents, your
employer, any noble person, and person you are flattering and
horses, because they are noble creatures.
Whereas, "How art thou?" would be appropriately said to your
spouse, your close friends, your children, your servants, any
person you are insulting, inanimate objects and Gods.
If you think about this list, you can see that nobody ever,
calls the Queen thou; and she doesn't have to call anyone you
--- unless she talks to her horse.
Don't make the mistake of assuming that thee and thou are only
two different forms of the same word, they aren't. Thou is a
subject of sentences, as in "What hast thou done?" and thee
is the object of sentances, as in "I shall tell thee a secret."
And what about all those antique verb forms -- those ost, est and
eth words? Well here are some examples:
I do Thou Dost
You do. He/She/It doth (or does)
I love Thou Lovest
You love. He/She/It Loveth
I have loved Thou hast loved
You have loved. He/She/It hath loved
As you can see, the antique verbs are used with the second person
intimate, the third person -- never with the first person.
Here's the possessive form:
Thy is a possessive used before a constant, "Thy rod, thy staff"
Thine is the possessive used before words beginning with a vowel,
"Thine eyes."
The same rules as above apply to my and mine.
The possesive for You doesn't change it is "Your."