I find it stupid how so many people are getting hacked, I've not once been hacked using msn/skype/runescape etc because you have to have common sense.
DON'T use your real DOB as people will know it
DON'T use an email anybody knows, you can hide this information.
Pretty obvious one is don't use a password that people would guess like "chloecat1"
To stop people from calling you who aren't in your contacts list go to;
Skype > Privacy >
Because I do know of a service going around calling people and being able to get to them somehow *not sure exactly how* but I doubt they're after Runescape items.
Common sense stuff really, people who get hacked are just morons in my eyes, been on the internet for easily over 5 years and never once been hacked on anything.