This is how I prepare my tomatoes for canning:
Halve or quarter
Toss in large bowl with-
About a TBSP of good Olive oil
1-3 crushed cloves of garlic
Italian Seasoning-about a teaspoon
I try not to season too much because I'm canning for use later and have found that I would rater the tomatoes be seasoned according to the recipe they are used in than to all taste like Italian style tomatoes so sometimes I omit the Italian seasoning.
After the tomatoes are prepared you can can them right away or cook them however you'd like but I like to roast mine in the oven. I usually roast them at 450 degrees arranged in a single layer face up for about 30-40 minutes. I use a sheet pan but make sure it has a rim so that the juices don't run off and make a mess in your oven. Plus you'll want to add any juice to the jars of tomatoes for extra flavor. when the tomatoes are all roasted fill hot clean jars, add about 2 TSP lemon juice to each jar and process for 85 minutes in a boiling water bath canner. Tomatoes take a while, yes, but are well worth the effort.