First watch the TV series all the way through, then watch End of Evangelion. Nothing else to it really.
Death and Rebirth is a clip show, don't bother with it unless you want to see all Eva-related material. Rebuild is fanservice disguised as a "retelling". It's not finished anyhow (one movie is out in the U.S., the other isn't even on DVD in Japan yet IIRC, and there's still something like 2-3 to go).
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