Selling directly to restaurants as a small vegetable farm

We grow mixed vegetables on eight hectares and sell mostly to a wholesaler at prices that barely cover costs. Several restaurants in the nearest city have shown interest in buying directly, especially specialty greens and heirloom tomatoes.

Direct sales mean weekly deliveries, invoicing, smaller quantities and planning crops around chefs' menus. We are thinking of starting with five restaurants and a fixed weekly list agreed each month. Farmers who supply restaurants directly: how do you handle pricing, delivery logistics and the unpredictability of harvests?