How do I get the soil ready?
Purchase a bunch of manure, try local farms they are usually very cheap or free. Turn this into the soil now.
Also buy some kelp meal to add when you are planting. Don't add it just yet.
You could also buy some Rock Phosphate and work that into the soil now. That wouldn't hurt at all.
How do I keep out squirrels and other animals?
Squirrels.... good luck. I've heard that pepper works. Cayenne was the recomondation but, I don't like causing them so much agony and just use black pepper. You can buy the jumbo sized ones for fairly cheap.
Rabbit and Deer, a fence. For deeer it needs to be at least 6 feet high and for rabbits, it should go right to the ground with netting or metal mesh. (That works like a trick of deer as well.)
Other animals, well ask and hopefuly you'll recieve an answer.
How do I water?
What you want to do is Deep Water. That means watering less often and for long periods of time so that the water can sink deep into the soil. So, what I do is water for at least an hour, about once a week or as needed. I actually water for about 4 hours.
The manure and kelp meal will work well but, you can buy liquid seaweed and liquid fish as weekly fertilzers as well. Dilute as per instructions on bottle. (Though I just add a glop to my watering can and filler up from there.)
Don't use synthetic fertilzers, they break down soil structure, kill beneficial soil biota and don't replace lost nutrients in the soil. Also, they can burn you plants.
In the fall, rake up the fallen leaves around your place and your neighbourhood and mulch them up with the lawn mower. Dig trenches in your garden and add the leaves to the trenches and cover the leaves with manure or coffee grounds or grass clippings and then either add another layer of leaves followed by soil or just cover with soil. I use the former method.
Then, lay a layer of leaves over the top of the soil of your garden followed by a layer of manure. Let this sit all winter long and in the spring you have luxurious soil that will give you copious amounts of fruits and vegetables. (And this stuff (the soil ammendments) are either free or dirt cheap.
Adding a little rock phosphate to the mix won't hurt either.
If you live near a coast and have access to a pickup truck throw some seaweed into the mix. Just add anoter layer of leaves on top of it followed by a final layer of manure.
I do many many layers in my SHEET COMPOST (described above) with different greens combine with different types of leaves (browns).
Don't use Oak leaves if you plan on growing corn and never use walnut leaves.