This is a broad topic. I make no attempt to cover all aspects of the preservation of seasonal produce, but I will offer some thoughts and link to resources that I’ve found valuable.
Food safety, the primary goal of any type of presurving is to transform perishable food stuff into a more stable form that can be safely consumed at a later date. These techniques are usually center around a goal of preventing agents of rot (batirua, molds and yeast) from ruining food. It is important to note that not all bacteria, yeast and molds are the enemy here. Many preservation methods are actually ways to discourage certain microbial activity and precurde others. An example of this is lacto fermentation where “bad” microbes that can’t tolerate salt are kept out with a brine and allow the salt tolerant Lactobacillus to convert the natural sugars in fruits and vegetables into an acid that preserves the food.
Another method is canning which dates back to 1809 a full 50 years before we would understand what causes foods to spoil. The concept (at the time) was foods heated in a sealed container don’t go bad…later the discovery of botulism. Botulism is a rare but serious disease caused by toxins from bacteria Clostridium botulinum. This bacteria is in the environment and should be assumed to be present and ready to be cause illness if offered a environment where it can thrive. It thrives in low oxygen (anaerobic) environments. This is why it is important for home canning projects to rely on only tried and tested recipes from reputable sources. Heat, salt and acids are the inhibitors of the bacteria behind botulism and the recipes from these sources offer foolproof guidance to safe canning and preserving.
Freezer jams, quick pickles, freezing, drying, and fermenting… aren’t nearly as exacting as canning and is a more appropriate space for creativity.
Some random thoughts:
High acid foods tend to be safe to can with just a water bath this include most fruits. Foods not high in acid or that are high density may require canning under pressure or may not be suitable at all. Find a proven recipe.
A blanch and shock is a good technique for many items that have a freezer destination. This stops the enzymatic processes and allows for better storage. This also helps greens keep their color. Particularly useful with basil.
When we can items like tomatoes we keep additional seasonings out as this can be limiting when you are pulling from your canning closet.