1) As from today I will start behaving better and doing everything you tell me to do right away.
2) I love you very much and appreciate everything you do to me.
3) Why don’t you want me to play with you?
As of today , I will start behaving better and doing everything you tell me to do right away. The use of 'from' sounds incorrect. So, 'of' can replace the preposition.
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As of today, I will start behaving better and doing everything you tell me to do right away.
I found only the first sentence incorrect. The other sentences don't seem to have any detectable mistakes.
Hope this helped you to clear the doubt.