You can make a simple cold frame to start seeds in. Make sure it faces south when you place it. You want the back higher than the front and you can make a simple top with an old window or make the frame for the lid and attach heavy duty clear plastic over it.
For Squash, cucumbers, tomatoes you can also grow them in containers. For vining type plants you can make a tepee trellis for them to climb up on. If you Tomatoe plants get to big, cut them back a bit and they will bush out. Also when transplanting tomato seedlings you want to bury them between half way and 3/4 way up. This will encourage deep rooting and make the plant stronger.
For those in dryer climates, or have hot spells, try taking 1 gallon milk jugs punch several holes in the bottom and lower sides, bury it next to the plants that need a lot of moisture, leaving the just the top part above ground. Fill it with water, this will also encourage deep rooting of the plants.
When you look for seeds for containers, look for ones marked "patio" also you want to pick determinant types. They will specify the size a plant will grow to and start producing.
For those with poor soil in the gardens try building some raised beds about 1 1/2' to two feet high. Dig out about a foot below ground put in some gravel, about 2-4 inches worth, lay some fabric cloth down over the gravel to prevent the dirt from clogging it. Fill with a good mixture of compost & soil. You can make hoop frames for the beds by using some PVC pipes or just get some of those Hula Hoops and cut them in half and cover with the clear plastic.
If you already have raised beds, you can cover them with black plastic over the winter. This will help heat them up earlier and help sterilize the soil.
For problems with rabbits, take blood meal and human hair and place it around your plants. The combination of the smell from the human hair and the blood meal will keep them away.
The only thing I can recommend at the moment for the tree rats is either a good dog or a 22 caliber bullet. Besides they make good eating!