During a first DIY service, what makes people nervous is usually not the task itself but uncertainty about when something might go wrong. The best cure for that feeling is preparation rather than blind confidence.
Start by finding out exactly what job you are about to do. Do not rely only on broad internet advice saying a model is always the same. Engine version, production year and even body style can change parts, fasteners and the order of the work.
Check the replacement parts physically before you begin. Does the new filter, seal or component actually look like what is coming off your car? Discovering the wrong part only after the old one is already removed is a classic beginner trap.
Prepare the workspace so that you have room to lay parts out in order, keep dirty and clean items separate, and leave the job unfinished safely if needed. A first service done in the rain, in the dark or on a slope does not make you smarter, it mostly just makes you tired.
Also gather the support items: gloves, paper towels, cleaning products, a suitable drain pan and a phone or notebook for notes. Small preparations save a surprising amount of running around and frustration.
It is very smart to have a backup plan. If something does not go as expected, can you refit the part, leave the car parked safely or call for help? That question is not pessimism, it is a normal part of sensible DIY work.
When you approach a job with preparation, even a first service becomes much calmer. Many DIY problems are caused not by difficult engineering, but by starting too fast and thinking too late.