Just make sure when you reconnect the terminals that they are all clean and in good condition, you dont get them mixed up (writing wire colours and terminal markings down helps).
There are 2 alternator types, and most suppliers will want the serial/part number of the old one, which is often not visible til you remove it. Also some suppliers only do exchange, so there will be a big surcharge if you dont take your old one in, but some just sell new ones.
Make sure you disconnect the battery first!