Well, First of all, I would wait until you have a specific problem. Many plants are pest-free are disease free, at least relatively so. In fact, choosing plants that are compatible with your environment is the first step to success. For example, if you live in a hot dry place, choose plants that like it hot and dry. Otherwise, you fight an uphill battle trying to make plants happy in an environment that they are not compatible with. If they are weakened, then they are more suspectible to plants and diseases. Also, try companion planting. Companion planting involves putting two or more plants together that natrually repell the other plant's problem pests.
http://www.attra.org/attra-pub/compl...aditionalAlso, make sure to fertilize your plants to keep them heathy, preferably with organic compost or other organic fertilziers such as fish oil. Try to stay away from harsh chemicals when you cam, they are bad for you to breath, not great for the environment, and can burn or damage your plants and beneficial insects too.For pest and fungicide, I like garden safe products.
http://www.gardensafe.com/ProductCategories/I have had good luck with the garden safe Neem product. It controls many common problems, such as pests like aphids AND diseases/problems like mold/virues/fungus. For birds, you can use a some type of scare tactics. They do not like shiny objects, so you can tie tin foil or cut-up tin pie plates to a pole, like a bamboo piece stuck in the ground, or to a fence to scare them off. You can also use evil eyes such as these
http://www.mastergardening.com/dee-2082.htmlFor squirrels and other pests, you can also make hot pepper spray
http://www.pallensmith.com/index.php... 09&aid=887For birds and deer, you can also use netting
http://www.gemplers.com/pestmgmt/wil...YAPMBAlthough, I have never needed to use the nets myself.Good luck!