Since most of the bases have been covered ^^^^^^ let me just add a few hints.....

Don't be afraid to modify or grind your own custom screwdriver bits! Even if you buy a complete Master set from Brownell's (Magna-tips are the best IMHO) there are still some times you need to modify one to fit properly. Replacement bits are cheap - don't try and use what you think is "good enough" because replacing most gun screws are a lot more expensive than replacing a Magna-tip bit!

Before just jumping in - make SURE you know all the little details for a specific job or task. Example: removing an ejector rod on a S&W Revolver requires at least every other chamber be loaded with EMPTY Cartridges to insure nothing bends or breaks. This is something many will forget to mention when telling how to do something and researching all the details BEFORE doing a job can and will save you grief and money.

Never try and do a GSing job in a limited amount of time! If you don't have the time - wait until you do.

Unless you are experienced and know exactly what yo are doing, do NOT use a Dremel, Belt Sander or Grinder on guns or parts! they remove way too much way too fast. Yes - they are useful down the road after you have gained experience and knowledge - but in the beginning, forget you own them (if you do).

If when doing a job you are unsure - STOP and ASK. Better to take longer and do it right the first time. There are many knowledgeable people here on the Forum. While there are a few good YouTube video guys out there, there are also many "Bubba basement hammer mechanics"who grab a camera and post a video when they themselves are not really qualified to do so.

When buying tools, it is better to buy less at a time and buy higher quality. Stay away from most Chinese tools. Ebay is your friend when it comes to quality Starrett, Brown & Sharp, etc. precision tools and punches and you can buy almost new tools (or very lightly used) for about the same price as new Chinese and imported tools cost in retail stores.