My personal rule is to always use 'me' unless the sentence can be rearranged so that if there were only one person being referred 'I would be correct.
So:
Example 1 You and I can go'. If it was just me , I'd say 'I can go'. If you say ' me can go' you can tell immediately that the 'me' in the first sentence is incorrect.
Example 2. '"would you give that to John and I?"? is wrong as you would never say ' Can you give that to I?'. So the correct version is ' Can you give that to John and me?'
I have no idea when you would use ' myself' and it sounds really clumsy so I never use it myself 
