Tips for tap washer? (budget keg)

[techtone]

The taps normally seem to come quite tightly done up but if you undo one it seems difficult to tighten up without causing the washer to splay. Anyone any good experiences/tips with this? I can't seem to even tighten one up to the point where it doesn't move when I rotate the end bit to align the tap vertically. Also anyone with experiences of whether it is best to use vaseline on the tap thread (and or washer) or not? I don't know if it would be better to warm up or cool down the washer?

[techtone]

Make sure the tap, keg and washer is dry and free from grease before tightening it.

Thanks. I gave it a very good clean/degrease and left to dry overnight. I have now got it nice and tight/secure.