The approach plate for an ILS is the way to go, and of course, a legal requirement for real world instrument flights.  I have access to terminal procedures through membership to the Airplane Owners and Pilots Association, but for simulation I sometimes just "wing it" to expedite landing at an airport I don't want to to take the time to download or look up.  The following works good for me when I am not trying to exercise real world proceeedures and should work adequately for those without access to approach plates:

Look up destination airport on the FSX map.  Note the airport winds, field elevation, and ILS equipped runways.  Select a runway taking best advantage of winds and note the localized frequency and approach course.  Also visualize an intercept course from current location to the beginning of the ILS course shown on the map.  Exit Map and return to flight, then setup localizer frequency and course.  Turn to intercept the localizer and navigate to around 2500 feet above field elevation (terrain permitting, otherwise adjust as needed)  Adjust intercept course enroute as needed (if GPS available, use as self-contained radar vectors to intercept point) and slow to approach speed.  Intercept localizer and turn on approach course.  Watch for glide path cues to become active and aircraft below the glide path.  Continue approach with normal ILS procedures (including intercepting the glide path from beloe) to landing or missed approach.

Happy flying,
GW