Well I plan on making a Bladesinger Gish for a new campaign I am running tomorrow. Should I consider going Favored Soul and Bladesinger? or should I focus purely on Bladesinger?
Also should I multiclass at all for Bladesinger and if so what class?
I would skip fighter and dip druid for shillelagh. Clerics already get armor, and dualing doesn't add much with 1 attack.Arcana Clerics from the SCAG can be gishy. Start with a Fighter dip for proficiencies and Dueling. Potent Spellcasting adds your Wis to cantrip damage, including the primary damage of Greenflame Blade and Boom Blade. Grab a ranged attack as your other free Wizard cantrip to give yourself a reliable ranged attack. Fire Bolt, Ray of Frost, and Chill Touch are all worthwhile choices, depending on your preference of damage type and rider.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.