There is no real quick and easy step-by-step as there are so many different things that could be the cause of issues, the PC, the Patch cables, the NIC, the switch port, the switch, the core switch, the router, the proxy, the server, things out side your network, configuration issues, vendors, user perceptions, and they all depend on what the problem being reported is. But the following would apply to everything, and anyone correct me if I am wrong. You need to narrow the scope of any problem to troubleshoot. For example, let's say someone calls up and says it take forever to get to www.cisco.com, well you need to find out what forever means and if it is just them or others, because I can't troubleshoot when people say it takes forever. So what you do is actually time how long it takes the user to open the webpage and compare the time with how long it takes you to get there. If the times match now you know it is not just that user. If they do not match and you are quicker than it could be somthing on the users PC or that users network connection but you have now narrowed it to that user or that users location, so I would have them ask a neighbor to time how long it takes them to get to the site. and so on until you narrow your problem down. The point is you need to find where the problem may be before you can start troubleshooting it. As for tools you will use ping, traceroute, sniffers, packet analizers, a ton of differnt switch and router commands, and a lot of other tools too many to list here, but a good engineer will narrow the problem quickly and then start finding the root cause and correct it.
Hope that helps,
Mike
