I'm looking into rebuilding my new old Subaru and know almost nothing when it comes to mechanics. That being said what are some common things to repair first and foremost?

 

Thank you.

Welcome!

 

You must provide further information about your Subie, such like Model \ Year / Engine, etc, and Photos, we Love photos here; but by your thread's title, I bet you have an EA82 engined Subaru, Sedan or Wagon. In my case, I would start by checking the Timing Belts and all the rubber Hoses, if the age of the Timing Belts is unknown, you must change them, along the tensioners and rods.

 

Here is a Guiding video, by MilesFox:

 

 

Kind Regards.

Welcome Kody!  I would suggest you spend time searching the USMB member posts and learn, take notes, and print out certain parts you feel apply to your car.  Secondly, early Subarus, by design, are pretty easy to work on.  So empower yourself and find online through eBay or Amazon the Factory Service Manuals (FSM) for your year Subaru.  These are vastly more helpful than the generic repair manuals you find at the local auto parts chain store.  There are lots of skilled Subaru wizards on USMB and they are a great resource.  Also this is a great place to buy or trade parts.  Ultimately you need to know what your doing and that it is done right.  All the best and let's see some photos of your new old Subaru!!! 

All 7 coolant hoses. Radiator condition. Check coolant level frequently. +1 timing belts and 3 idlers.

After that, then comes the Axles...