Starting seedlings too early indoors makes them difficult to care for. Start the seedlings so that you allow a maximum of 6 weeks growth indoors before transplant time. Many Demonstration Gardens wait to set tomatoes and squash out until the first weekend in June. Cover them with floating row cover, boxes, plastic jugs, or plastic covers to protect them. Some gardeners keep tomatoes, peppers, and eggplant under covers until July for best growth get them planted but give them shelter from cold.
Hand pick the critters off, and try putting metal copper barriers around raised vegetable beds.
A half barrel of lettuce, for instance, can be protected quite a bit against slug damage by being wrapped with a ring of copper. The copper bands seem to work best if they are 3 to 3 inches wide, so it's necessary to place two or three bands side by side if they are very narrow. If you choose to use slug baits, place the bait carefully in covered containers. A yogurt container or a margarine tub works well. Remove the lid and clean the container.