Here is my simplistic answer: "to me" = in my opinion or viewpoint "for me" = in my case or circumstances. To me, it's not necessary. (that's my opinion) For me, that would be a disaster. (in my case, those circumstances would be a disaster for me) We GIVE something TO someone always. He gave it to me. I gave it to him. (there is no 'for' in this usage)

These are somewhat interchangeable but not totally. I might say "for me" to show my opinion, especially the phrase "as for me..." That shows that my opinion may contrast with those around me. "To me" can also express opinion, but more "in my eyes." "That is beautiful to me." Also you might give something to me but do something for me. That's a difference that is due to the choice of verb. If you do something for me you do a favor or a kindness. If you do something to me you affect my person some way, usually negative. Switching the order doesn't really change the meaning, except that putting "to me/for me" up front adds emphasis. "For me, that would be a disaster." --- That would be a disaster for me but not necessarily for other people. "That would be a disaster for me." --- That would still be a disaster, but no implications about others. Ex 2. Those would have the same meaning. No problem either way. Hope that helps!