Whenever the engine fails in a single engine aircraft, the first two chex must be:
1. Attain and maintain best glide speed.
2. Pick a suitable place for a landing.
After that, everything else is a bonus and will depend on how much time you have. If you are short of time, then tighten straps and maybe switch off fuel etc. More time, then tell someone. Even more time, maybe start to trouble shoot, but not at the expense of screwing up the forced landing.