Start at the beginning. 
Rome wasn't built in a day. 
If it ain't broke, don't fix it.

It helps it you plug it in. 
It helps if you turn it on. 
When all else fails, read the manual. 
 
Learn the rules and jargon. 
Backup, backup, backup.

The younger they are the more PC literate they are. 
The younger they are the more impatient they are. 
Boys typically know more (about computers) than girls. Technology is a guy thing.

Garbage in = Garbage out. The cheapest products usually aren't. Products are either inexpensive or easy to use -- not both. Tomorrow's will be faster, smaller and less expensive.

All roads lead back to your dealer. Buy locally. It costs less. Don't assume the worst -- most problems are easily fixed. Don't try to fix hardware yourself -- leave that to the pros. Play solitaire -- it is good mouse practice. 

Don't listen to every user you know -- most are dumber than you. Find one "expert" friend and stick with him or her. Keep it simple. Ask 12 people, you'll get 12 different answers. All may be correct, but in the end you will have to choose one idea to implement.

Is you computer too old?
Yes if it doesn't run Windows 95 or later.
Yes if it doesn't include a CD-ROM drive.
Yes if it can't reach the Internet.

Should I buy a Mac?
There are easier ways to live on an island.