1) Build UFO Yard
2) Recover UFO
3) Research UFO Theory
4) Research UFO - [Insert Type Here]
5) Disassemble UFO
6) Repeat steps 2, 4 and 5 as needed
Edit:
I forgot to mention you want your UFO Yards built on top of - or as near as possible - your production (preferably a disassembly dedicated one) base as distance increases the disassembly time, also disassembling a damaged UFO and an intact one takes the same time so plan accordingly.