FORMS OF ADDRESS - SHORT FORM
addressee's rank direct address reference to
none/unknown my lord, my lady, m'lord, m'lady by first name - no title
AoA Lord [Name], Lady [Name] Lord [Name], Lady [Name]
GoA Lord [Name], Lady [Name] His Lordship, Her Ladyship Your Lord/Ladyship the Honourable Lord/Lady [Name]
PoA (Peers - knights) Sir [Name], Dame [Name] Sir [Name], Dame [Name]
PoA (OL, OP) Master [Name], Dame [Name] Master [Name], Dame [Name] Mistress [Name] Mistress [Name]
Baron/Baroness Your Excellency Baron [Name], Baroness [Name] Baron [Name], Baroness [Name] His/Her Excellency My Lord Baron/My Lady Baroness
Viscount/Viscountess Your Excellency Viscount [Name] Viscount/Viscountess [Name] Viscountess [Name] My Lord Viscount His/Her Excellency My Lady Viscountess
Count/Countess/Earl Your Excellency Count [Name], Earl [Name] Count/Countess/Earl [Name] Countess [Name] His/Her Excellency
Duke/Duchess Your Grace Duke [Name], Duchess [Name] Duke/Duchess [Name] His/Her Grace My Lord Duke, My Lady Duchess
Crown Prince/Princess Your Royal Highness His/Her Royal Highness Your Highness His/Her Highness
The Coronet (as an institution) Their Royal Highnesses
Queen Your Majesty Her Majesty My Lady Queen Her Royal Majesty
King Your Majesty His Majesty My Lord King His Royal Majesty Sire My Leige (if you're in direct fealty to him)
The Crown (as an institution) Their Royal Majesties
The Dowager Princess Janeltis Her Serene Highness
NOTES: ANYONE may be addressed as "my lord" or "my lady", regardless of rank, as this is the correct form of address for all of noble birth. When in doubt, use it. No offense should be taken, and if it is, it's not your fault.
AoA = Award of Arms, given without any other award in An Tir.
GoA = Grant of Arms, given with entry into the Orders of The Goutte de Sang, The Jambe de Lion, or The White Scarf, or when awarded the Grey Goose Shaft or the Hasta Leonis.
PoA = Patent of Arms, awarded with entry into the Chivalry, Order of the Pelican or Order of the Laurel, and also given with a Royal Peerage (Duke/Duchess/Count/Earl/Countess/Viscount/Viscountess).
Peer = a Laurel, Pelican, Knight, Master at Arms. Viscount is pronounced VY-count (long i, silent s). Viscountess is pronounced VY-count-ess (long i, silent middle s). Jarl is the Anglo-Saxon equivalent to Earl, its feminine form is Jarla - Jarl is pronounced YARL (rhymes with Carl). There are various other alternate titles in use.
The official list can be found at http://www.sca.org/heraldry/titles.html Titles other than are on this list are also used - if in doubt ask the person you're addressing for their preferred form of address; this question is very nearly always received as an honor.
A list of An Tir awards is at http://www.antir.sca.org/Pubs/ATH/6awards.html
More about Her Serene Highness Janeltis can be found at http://www.antir.sca.org/WhosWho/janeltis.html