A simply mechanics rule is to fix the easy things first. Salt that with knowledge of what commonly goes wrong, and in your case the recipe is to replace the sending unit (easy to do, around $16 at Kragens) and see if the gauge starts reading correctly. My gauge shows 60-70 psi when cold and starting up, which drops to 40 with the engine warm and at idle. Danger low is 8psi, which is when oil pressure warning lights come on. If you're above 30 I'd feel safe, though many people claim to get by with 20+.
If after replacing the sending unit and confirming the wiring is working, next step would be to confirm the oil pressure. For this a mechanical gauge is relatively cheap and easy to install.
If the mechanical gauge confirms low pressure, then it's time to fix the problem: old/tired engine? plugged baffle on oil pickup? etc. Pickup the factory service manual and it gives you some nice diagnostic charts to help you through this...
Short answer to all this is: get the factory service manual