Aside from skill level, technical knowledge or even simple curiosity, there are two things anyone attempting to self-diagnose or repair their PC will need: proper tools and adequate safety precautions. You can’t fix things without the right tools for the job, and if you’re not being safe you’re asking for a world of hurt (and potential data loss)
You wouldn’t drive a car without a seat belt. You wouldn’t ride a motorcycle without a helmet. So it stands to reason, you don’t like getting hurt or taking needless risk. So consider the computer. IT does a lot of things, and they all require one thing above all else: electricity. Lots of it. There are many high-voltage components inside any PC – the power supply above all others. Taking precautions to avoid electric shock (or worse) is critical. Electrostatic discharge (ESD) is another killer – of components. ESD can ruin sensitive electronics and render expensive hardware useless.
What to do?
Disconnect power and allow discharge before servicing hardware. Unplug, flip switches, and if you’re dealing with a laptop with a removable battery, remove it. Hold the power button for about 15 seconds to discharge any retained power. If something says “No serviceable parts inside”, don’t question it. Power supplies are well-known for these warnings, with good reason. High-voltage capacitors can pack a NASTY bite, and power supplies are full of them.
For ESD, many will recommend an anti-static wrist strap. These are basically a plastic or rubberized wristband with a coiled wire cable that connects you to a grounding surface, usually the metal case of your PC or even just a metal table leg. The wire connects to a resistor in the strap, intended to slowly and safely discharge electrostatic buildup as you work. You can achieve a similar effect by placing both hands on the metal parts of your computer case.
Even the most skilled and capable techs aren’t useful to anyone without the right tools. Maybe you need a phillips screwdriver? Perhaps a Torx or Hex key? Laptops require smaller micro drivers, and for electrical testing you want a multimeter. More advanced testing often requires bootable media on either a CD/DVD or a flash drive. You may even want a separate, fully-functional machine with a hard drive dock fro virus scans and drive diagnostics. (Or maybe you’d rather leave that you a trusted PC repair professional).
Keep all of this in mind as you go through any DIY process to minimize your risks and maximize your effectiveness. Or just to gauge how far you are comfortable working or learning.