From reading the title "Stopping by Woods on a Snowy Evening" I think the author is going to talk about a journey he takes on a snowy evening in which he stops for some reason.
A - Attitude/Tone
In the first 3 lines the poet arrives to the woods and wants to stop, he knows that the owner of the woods lives in the village so he will not see him. The next few lines explain that the poet wants to stop to watch the woods fill up with snow, he knows his horse will think this is odd but he does it anyways. He soon realizes he has made promises to be somewhere and he decides to carry on with his trip.
S - Shifts
In lines 15 and 16 the poet says "And miles to go before I sleep." He doesn't actually mean that he has miles to go, he is referring to the years he has until his death. Poet's often use metaphors to express different meanings.
T - Title/Theme
The words that create the attitude in the poem are dark, deep, lovely, windy, and mistake. These create a darker tone.
The speaker's attitude changes when he says "but" in line 14. He says this because he realizes that he needs to stop watching the snow and get on his way because he has made promises to be somewhere.
Now that I look at the title I realize it means the poet is on a journey where he cannot stop, even though temptations throughout the way make him want to stop he can't, because he has places to be and promises to keep. The theme of this poem is how the desire of peace of mind can easily be interrupted by everyday events and even though it is hard to get past you have to keep in mind what is important and persevere through.