How often should I clean out inside my computer?
Every couple of months use a can of compressed air to clean out your CPU.  First remove the side wall of the unit, then  keeping the can upright, spray away the dust, paying particular attention to the fans. When you’re done you can carefully vacuum the dust from around your computer and the bottom the unit. 

When should I contact a computer repair professional?
Call a professional when you encounter a recurring or severe error that is not remedied by rebooting your machine or running your virus protection/spyware software.

Should I use adware and spyware removers along with my virus protection software?
Adware and Spyware are not viruses, so your virus protection software may not protect your computer from them, using a separate program for them may be necessary.