Do yourself a favor and clean the bulb socket with some contact cleaner and apply a tiny bit of dielectric grease to the bulb base before you put in a new bulb.
Be sure to never touch the new bulb with bare hands when installing. Wipe the bulb with a clean, dry, lint free cloth to insure no residue or finger oil resides on the bulb before turning it on for the first time.
After showing a film, always run the projector fan with the lamp off until it is cool. The bulb will last longer.
If the bulb can be obtained in a lower wattage with the proper base orientation, choose the lower wattage bulb. Unless you are showing an auditorium full of people your films, you can use a 500 watt with ease, whereas a 1000 watt bulb will heat up a room like a bomb and shorten the life of your film.