This is a slightly expanded version of some tips I posed on the Chicago.localvores.org site.
Wisdom gleamed from nearly 3 years of attempting to eat local:
Be realistic. I like the challenge aspect of eating local, but I do not believe I need to deprive myself of items that make sense. I'm not giving up coffee; I'm cooking with olive oil; I'll buy some bananas. I do have a rough system to what I will eat non-local. It has to carry. It should be a product that is meant to be eaten beyond its boundaries. Put another way, could you have eaten it in Chicago 50 years ago. I think by allowing myself certain things, it makes the overall dedication to localism that much easier. Don't make yourself crazy. Eating local will grow on you.
(I should add that we have no eat local restrictions when we eat out. It is not as if a shrimp or a mango never touches my lips.)
It takes time. Time to know sources. Time to know what to put away. Time to know what works. We are so disconnected from our historical farming/eating habits. You just cannot reconnect. Local does not happen in a day. My wife and I still marvel at how naive we were on our long ago first visit to the Oak Park Farmer's Market. How we were disappointed with its seeming bareness. Now, we know what to expect in the Spring, come Summer, Fall, and especially, what it's like living through the non-market months. We know because we've been doing it. We still learn, and we expect to be better local eaters next year.
Eating local does not end when the farmers markets pull up their stakes. One must take advantage of the fuller months. My CSA box this week features a huge bag of green beans, five or so zucchini and 8 ears of corn. All of this stuff is not meant to be eaten now. I'll pickle some of the zuke and freeze all the beans and some of the corn. Eating local requires a commitment to eat what's in season and what's not in season. Eat your full of asparagus in June, but also eat your asparagus in January. Freezing is easy, although freezing space can be an issue. A full size freezer is not that expensive, as things go. My wife and I are still neophytes when it comes to other preserving measures: drying, pickling, canning. As I said above, eating local just does not happen. It takes time to learn to do the things necessary.
Local is where you find it OR (as Mad-Eye Moody would say) constant vigilance. You may find Michigan apples and Washington apples at your supermarket. Well, did you know there would be Michigan? Do you know there are often Wisconsin potatoes as well as Idaho. Seek out the local and then buy the local.
Build relationships with farmers. This last one is so key. You might be able to buy fresh produce, in Chicago, in the dead of winter. You can purchase home canned foods if you are a CSA member (and your CSA farmer cans). Or you get the inside scoop on cows, lambs, pigs, buying bulk to save $$ Full consumption of local meat was our biggest hurdle, and it was a cost issue. Meat raised locally and sold at farmers markets is very expensive. This cost gets drastically reduced when buying in bulk. While it is possible to find farmers selling whole, 1/2 and 1/4 animals on the 'net, it is easier and more reliable to know a farmer that will sell directly to you. My fascination, respect and interest in our local farmers helped drive me to eat local. Their returned favor has made it a lot easier.