First off have a decent computer, if not, take a look at this build I have that will run most graphically intensive games at a steady 50 maybe 60 frames per second:
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel Core i5-4690K 3.5GHz Quad-Core Processor ($199.99 @ Micro Center)
CPU Cooler: Corsair H100i 77.0 CFM Liquid CPU Cooler ($89.99 @ Newegg)
Motherboard: MSI Z97-GAMING 5 ATX LGA1150 Motherboard ($149.99 @ Newegg)
Memory: Kingston Fury Black Series 16GB (2 x 8GB) DDR3-1866 Memory ($164.99 @ NCIX US)
Storage: Samsung 840 EVO 250GB 2.5" Solid State Drive ($118.99 @ Best Buy)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($53.98 @ OutletPC)
Video Card: EVGA GeForce GTX 770 2GB Superclocked ACX Video Card ($309.99 @ Newegg)
Case: NZXT H440 (Green/Black) ATX Mid Tower Case ($109.99 @ Micro Center)
Power Supply: Corsair RM 650W 80+ Gold Certified Fully-Modular ATX Power Supply ($99.99 @ Micro Center)
Operating System: Microsoft Windows 8.1 (OEM) (64-bit) ($102.98 @ Newegg)
Monitor: Asus VS247H-P 23.6" Monitor ($147.58 @ Newegg)
Total: $1528.46
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2014-09-11 17:26 EDT-0400
For a microphone, try the Blue Snowball, I love mine.
Video editing software, I like Sony Vegas but it is too expensive for my taste and I am not going to do anything illegal to get it, so Sony Movie Studio is very similar and very good.
Recording software, buy fraps, it's great for the price
You could try a webcam, but I prefer camcorders for recording.
Lastly if you like music, gaming, and editing, I use headphones for all those, take a look at the Audio Technica ATH M-50s.
This will provide a great start to a great YouTube channel