I have a brown thumb. I try every year though. Could someone please tell me some fail-safe plants that I could grow in Maine, when to put them out, and any growing tips?
What in particular are you looking for? Both fruits & vegetables?
Fruit: Raspberries seem pretty easy-going to me. Fruit trees too, just remember to keep them well watered for the first few years.
Vegetables: Radishes, "wild" green mixes, potatoes, squashes, peas/beans.
Those are suggestions based upon my opinion, others may disagree or have other suggestions.
I'd say start relatively small and try to research what each crop needs to be healthiest. Often the hard-to-grow plants are just more picky and if you learn what they like best and try to provide it, they aren't really that hard to grow after all.
Starting small is good, because it allows you to be more attentive, which I think is often the key to having a green thumb (having the time to hover over your plants, if need be).
Spring is often the best time to start or transplant most plants.
Growing tips are easy to find in a good gardening book or even by searching the internet. If you have a specific question about a specific crop, I'm sure someone here can help too.
You know, in a few weeks you may want to start some fall bulbs. When they come up in the spring it will give you a little warm feeling inside and you'll be ready to try some spring planting then!
You might be better to look for seeds that are suited to your particular climate. Using seeds instead of the seedlings at the garden center gives you a WIDE variety of veggies to choose from. I think tomatoes (a short-season variety) are pretty easy, as are cucumbers. Bush beans are pretty easy, too.