2005 Subaru Outback will not start

Remove and THOROUGHLY clean the old copper connector rings with a steel wire brush and/or sandpaper. Then charge your battery and retest over time. If no good you got a bad battery. That said, it's not a bad idea to change your plugs over to the newer iridium tipped ones that'll outlast you...nevermind your aged-out Subie. Dry and inspect cable boots for excess oil; if really wet change to 10w40 oil year-round, or even 20w50 summer, adding a bottle of stop-leak additive to swell those weeping spark plug seals. If your starter cranks strongly often, but not at all sometimes...AND it's not the battery, your starter copper solenoid contacts have worn out. They're about $15/pr but removing the starter's LOWER bolt is hard to reach unless you're under the car. Have fun, fun start with the easy stuff, like the crappy battery cable clamps (replace with cheap alloy ones for $2 if necessary) Ern TSG/B