A dissertation is very much like a bungalow made with heart. It has to be compact at the plinth; exterior aspect; inner space, frontal grace; everywhere. You have to grade it with bitumen of strength at all junctures.
Of course, the two areas which naturally interest readers the most are the Introduction and Conclusion. They are the starting and ending points and should carry something extra; on the aesthetic and poignant level.
Yet another important segment is the discussion; or the analyses of your methods if you will. Here is the first time you give reasons behind your earlier assertions by coming to acute inferences.
Now, while writing a discussion, you are of course guided by the methods. You have to mix and merge the findings of your method and conjure an analysis which strengthens your view of the topic.
You should be fair to the methods; not prejudicial. Your tone needs to be objective and should not play to the gallery. You should write the discussion in eponymous mode; automatically involving readers to think of their suggestions. This is especially so when it is not an expository paper.
Regarding the conclusion, there is one thing clear. You cannot bring something to the fore which you have not discussed in the earlier segments. It has to be a careful assimilation of the emphatic points you have placed in junctures. You also have to glean out the mains from your findings and analyses.
A good conclusion always seeks a clear and free path. It tries to turn the topical theme towards liberty. This becomes pivotal when the topic encompasses a great populace; as they get an idea on how to negotiate the pertinent problems.
Your conclusion should be assertive, with no dilemma or confusion thrown in. You should appear to have eternal grasp on the theme and your conclusion should seem carved out of your authority on the topic. This makes the paper redoubtable.
Of course, the discussion and conclusion will merit attention when you pay attention to the preceding segments. The sequential progression; fervent Methods and a compact writing style are the armory you should build on.
You should always pick a dissertation topic you feel you know about and are encouraged to learn more about. Do not go against the veins of your heart; you will create a half-baked preparation. Listen to your heart and then the mind.