When approaching a 25 mark question such as this the most important advice to remember is: argue from evidence. Every point you make must be backed up by the latin text, preferably with a style comment which emphasises the meaning.
Usually this sort of question would be attached to a short passage of text, however in the part (b) question it is also required of you to refer to the rest of the text. In the part (b) the argue from evidence rule still applies, however, it is certainly not imperative to memorise quotes from the latin. I would recommend commiting some paraphrased key english quotes to memory.
This question is a section (a) question and let's use lines 54-73 to answer it. This exam is time pressured and a common error candidates make is to make their (a) answers overly stylistic, which is unneeded and costs time. This style should be saved for the (b) answers. Although answers for (a) need not be overly stylistic, the following are important: overall coherence (your argument is consistent throughout the answer), close text analysis and a conclusion.
Your answer needs to be an argument. With this particular question you are simply putting forward ways in which Virgil presents Dido as "increasingly desperate" and explaining the implications of this presentation (i.e there's no need for an argument for & against the question in this case). The second part of the question requires some contextual knowledge, that Dido's attempts to receive the pax deorum are futile and despite her desperation she is unsuccessful and so is in store for a grisly ending.
Evidence you may wish to consider.
Lines 54-55: decreasing tricolon (1) "animum" [heart], (2) "spem" [mind], (3) "pudorem" [conscience]. The effect of the tricolon is that it emphasises how Dido's love for Aeneas consumes every part of her until she reaches a point where she is no longer able to make sane decisions. This idea is reinforced by the emphatic placement of "spem" and "pudorem" at the beginnings of their lines.
Line 56: the plurality of the words "delubra...per aras" [temples...at the altars].This reveals how hard Dido tries in her desperation to achieve the pax deorum that she visits multiple temples and shrines in her need to achieve divine approval. The plurality also suggests that divine approval will be difficult, if not impossible to achieve.
Lines 58-59: emphatic placement of the words "legiferae" [as law prescribed] and "Iunoni ante omnis" [above all, to Juno] at the beginnings of their lines. These reveal how Dido attempts to perform her sacrifices in as correct a way as she is able, in order to grant her the best possible chance of receiving the pax deorum. Again, this can be flipped round, as the great pains she has to go to to ensure that she is ritually sound imply that she is conscious that she won't receive the pax deorum.
Line 60: hyperbaton and placement of "ipsa...Dido" [Dido herself] which frame the line. This emphasises how Dido herself (and no one else) performed the most serious (and bloody) sacrifice on her own in her desperation to receive the pax deorum. The extreme lengths she goes to on her own could also suggest the impossible nature of her task.
Line 62-63: the words "spatiatur" [she moves slowly] and "instauratque diem donis" [and she renews the day with offerings]. She walks in a stately measure and performs her sacrifices as traditionally as possible. This technical vocabulary and conduct reveals her desperate to get this sacrifice right.
Line 64: the meter reveals a 2nd foot arsis. The meter stops with the long syllabul and so emphasises the word "inhians" [peering into]. We are left with the poignant image of Dido desperately searching the entrails of the cow for a favourable sign. However this desperate search implies that there is no favourable omen to be found, the outcome will be disastrous.
Lines 65, 68, 69: words such as "furentem" [raging], infelix [doomed], "furens" [raging]. Dido is desperately out of her mind and is burning out, she is entirely doomed for disaster. These words constantly remind us through this passage that although Dido does everything she can and in the correct manner, nothing could be enough and she is fated for doom.
Lines 66-67: The words "flamma" [flame], "medullas" [marrow of the bones], "tacitum" [silent], "vulnus" [wound]. Each of these words refers back to the beginning of the poem and have corresponding meanings. "flamma" refers back to the word "ignis" line 2. "medullas" refers back to the word "venis" line 1. tacitum refers back to the word "iaeco" line 2. "vulnus" refers to the word "vulnus" line 2. The effect of this correspondence is to reveal that Dido's doom is consistent and has been fated since the beginning of the book.
Line 68: the emphatic placement of the words "virtur" [was on fire] and "vagatur" [she wandered] at the beginning and end of the line. Her love is damaging and she is increasingly out of control, no longer able to made sane decisions but consumed by the fire of her passion.
Lines 69-73: the simile in which Dido is compared to a deer being shot by a shephard reveals to us Dido's hopeless love for Aeneas. The setting of the simile in a "nemora" [a grove] contrasts with the setting of Dido's love affair in her own city. In this way it is almost as if every part of the city (and ordered society) is stripped away and all that we are left with the wild nature of the forest. The word "incautam" [off one's guard] ascribed to Dido and the similar description of Aeneas as "nescius" [unaware] creates a parallel of unexpected love between the pair. Dido does not expect to fall in love following the death of her first husband, and Aeneas has no idea as to the extent ot the effect he has had on her. Moreover the characterisation of Dido as a "cerva" [a deer] emphasises her vulnerability and her inability to run away from her passion (fuga).
Line 73: the alliteratively chiastic construction of "haeret [A] lateri [B] letalis [B] harundo [A]" [fast to her side clings the deadly flank]. This construction is very emphatic and shows just how doomed Dido is. It reminds us that she was unsuccessful in achieving the pax deorum, her terrible fate awaits.
At the end of your answer it is then important to summarise your points concisely and quickly in a short and punchy fashion. For example: "In conclusion Virgil reveals how Dido becomes more and more desperate in her attempts to achieve the pax deorum, trying at multiple temples and eventually performing the most bloody, disgusting sacrifices, unbecoming of a queen. Virgil also reminds us of how doomed Dido is throughout this passage, how her desperate attempts reflect her own knowledge that she will fail in her request."