From Mark itself and no cross-references, here are my own notes in breaking apart and understanding Mark 13 as a whole.
Jesus foretold the destruction of the temple (Mark 13:1–2), provoking two questions by four of the disciples about the timing of the final judgment: “when will these things be, and what will be the sign when all these things are about to be accomplished?” (Mark 13:4). In Mark 13:5–37, Jesus explained when the judgment would be and what sign would precede this end.
In Mark 13:5–8, Jesus stated that “the beginning of the birth pains” would include many saying, “I am he!” (i.e., the Christ). There would be wars, rumors of wars, earthquakes, and famines. Concerning the false christs, Jesus admonished, “See that no one leads you astray” (Mark 13:5). Of the catastrophes, “Do not be alarmed” (Mark 13:7).
In Mark 13:9–13, Jesus prophesied that the world would hate His followers, arrest them, beat them, and that the Spirit would give them the words to say at this time. The gospel would thus be proclaimed to the nations. In light of such danger, Jesus admonished, “Be on your guard” (13:9). Concerning the Spirit’s help, He commanded, “Do not be anxious beforehand what you are to say, but say whatever is given you in that hour” (Mark 13:11).
In Mark 13:14–23, the sight of “the abomination of desolation” would indicate increased danger at this time. Jesus described this time as “in those days” (Mark 13:17, 19) and “the days” (Mark 13:20, 2x) marked by “such tribulation” (Mark 13:19), that is, “that tribulation” after which other events occur (Mark 13:24; cf. 13:24–31). The commands given here tell of a time of great urgency: “let those . . . flee” (Mark 13:14); “Let the one . . . not go down, nor enter” (Mark 13:15); “let the one . . . not turn back” (13:16); “Pray that it may not happen in winter” (Mark 13:18); “do not believe it” (when someone claims to be Christ; Mark 13:21); and “be on guard” (Mark 13:23).
In Mark 13:24–31, after “that tribulation,” judgment “in those days” continues (Mark 13:24). The sun, moon, and stars are affected, and the Son of Man comes in the clouds and sends His angels to gather the elect. Just as the fig tree’s tender, leafy branch indicates summer is near, so also do these specific events indicate that Jesus “is near, at the very gates” (Mark 13:29) and will come once and for all (cf. 13:26, 35, 36). The generation of unbelieving Jews in Jesus day continues on today until His final coming takes place (Mark 13:30). No commands are given here. Jesus simply notes that “when you see these things taking place, you know that he is near” (Mark 13:29).
Finally, after detailing the many signs that would precede “when all these things are about to be accomplished” (Mark 13:4), Jesus specifically describes the timing of “these things” in Mark 13:32–37. They take place in “that day,” “that hour,” which “no one knows” and “you do not know” (Mark 13:32, 33, 35). Because we do not know, we are commanded to “Be on guard” (Mark 13:33), “keep awake” (Mark 13:33), and “stay awake” (Mark 13:35, 37).