Honestly you won't find such guide.
Almost every level from 1 to 99 can be used for a specific task (from VLLD rare items to Griffon's Eye).
Just keep in mind you want char level 95+ to gamble rare amulets with +2 class skills,
char level 92+ to gamble rare circlets with +2 class skills,
char level 91+ to gamble rare pvm rings (with mana leech),
char level 87+ to gamble coronets/tiaras/diadems with +2 class skills,
char level 79 exactly to gamble rare HLD pvp rings.