I've recently moved into a home with a gas oven, but I've never used a gas oven before. What general differences might I expect compared to cooking in an electric oven? Humidity? Cook times? What rack setting to use? What temperature to use? Different cooking characteristics? Etc.
My experience with gas ovens is that they are much more susceptible to heat 'zones'. The top of the oven is markedly hotter than the bottom, and the back, nearer the flame, is hotter than the front. Other than that they are pretty similar to electric ovens.
Gas ovens may use gas mark settings rather than a temperature scale - converters abound online if so.
In almost all respects, cooking in a gas oven is the same as cooking in an electric oven.
Some differences you may find:
While it is technically true that gas ovens are less airtight, and slightly more humid (due to water produced as a byproduct of burning the natural gas) than electric ovens, in practice this makes little difference at all.
You still want to cook by temperature, not by "mark" or "dial" setting. You should get an oven thermometer if you don't already have one, to calibrate that setting shown on the dial or control matches the actual temperature inside the oven, at least to within 25 degrees F (or about 10 degrees C) or so.
You will actually find more differences just as variance from one oven to another—some bake a little hot, or a little cold. Others have different hot spots or heat circulation patterns.
Baking some simple cookies or sheet cakes that you know well, and monitoring the results should help you get used to any adjustments you need to make for your new oven. Of course, so will the oven thermometer!