The Support section on ntp.isc.org has a lot of useful information.
If you just want to use the pool, see the pool usage page.
The comp.protocols.time.ntp newsgroup is the best place to get help with the ntpd software.
Below are some things of particular importance if you are going to join the NTP Pool with your server.
To work properly ntpd needs to talk to at least 3 servers ("A man with a watch knows what time it is. A man with two watches is never sure"). If you configure your ntpd with five then it'll work well even if one or two "goes out" for an extended period. If you configure too many you are just wasting resources (or eventually confusing your ntpd!)
Ironically to make sure the pool service is the best it can be you shouldn't use the *.pool.ntp.org aliases in your configuration when you are going to add your server to the pool.
We don't want to risk having the pool servers just sync time "amongst themselves". For the robustness of the pool it's healthier if all pool operators "hand pick" good local (network wise) time servers. The NTP Community Site maintains a list of public servers.
We are all for software diversity, but a significant percentage of the "it's not working" questions that come in are for software other than ntpd.
You can use the pool with any program speaking NTP, but if you are going to join the pool we recommend you use ntpd.
In most scenarios it's not correct to have the LOCAL clock driver configured.
You should only configure the LOCAL clock driver if you want your ntpd to serve time to your local network in the case of a network outage (to keep all local systems in sync even if they drift from the UTC time).
Some linux distributions defaults to only allowing an application to lock 32KB memory. An ntpd in the pool requires more than that. In the ntpd startup script (often /etc/init.d/ntpd) add this before ntpd is started:
ulimit -l 8192
There's a known problem with the x86_64 package in RHEL4 U2. There's a link to an updated .src.rpm in that bug posting. (Or you can download a built rpm: ntp-4.2.0.a.20050816-10.x86_64.rpm (no warranty, etc etc).