Steal from your grandpa and remember the below 4S!
Shirt-Take one white with bright colour on it, it must have the 70’s feel
Shorts-Wear a girly colour one to make the outfit looks chic, the model above is wearing a pink one with roses
Shoes-Wear a girly ballet shoes
Suspenders-Wear them to achieve a GRANPA look, you could also be creative and wear them backwards
P/s: The shorts has like chiffon rosettes (cloth stiches into bundles which looks like roses) on it, those roses are not a print on the shorts. The roses is actually something like this
Sorry for my lack of drawing skills :)
Hope you guys like it :D