Here's the approximate recipe for my Strawberry Shortcake:
75% Unflavored base liquid
10% FlavourArt Strawberry
10% FlavourArt Vienna Cream
3% Perfumer's Apprentice Graham Cracker
2% Perfumer's Apprentice Vanilla Bean Ice Cream
If you premix your flavoring, these would be ratios:
40% FA Strawberry
40% FA Vienna Cream
12% PA Graham Cracker
8% PA Vanilla Bean IC
You can substitute different brands, but I don't know of an equivalent for Vienna Cream or Graham Cracker. Capella Vanilla Custard can probably be used in place of PA Vanilla Bean Ice Cream.