The general theme of the Psalm is asking for help and safety from dangers and pitfalls. During 10 days of Teshuva, we are "beinonim" - i.e. - the fate of our future awaits in G-d's hands (a recurring theme mentioned esp. in UN'Taneh Tokef, among other prayers.) We ask G-d to listen to us and we pray that He will seal us in the book of life. We pray that we be successful in our endeavors, but we also need G-d's help to do that - a theme mentioned in this Psalm.
Another concept is alluded to by Torah Temimah which says that this Psalm is a reference to Abraham praying for G-d's help for a miracle to occur so that he wouldn't have to sacrifice Yitzhak. The theme of the Akeida and Yitzhak is associated with Rosh Hashannah.
Although not mentioned in Torah Temimah (at least, I don't see it, there,) I assume that the "mountain" referred to in the 1st verse may be an allusion to Mt. Moriah.