Everything from the 1 lessons of this topic on a few pages: the key idea of each lesson, the diagram to remember, the points to learn and the traps examiners set. Read it, cover it, test yourself.
Organic synthesis means making a target molecule from a starting material by a sequence of known reactions. First identify the functional groups present, because each group has its own reactions and tests. Then work backwards from the target: compare the carbon skeleton and functional group of the target with the starting material. If the number of carbon atoms goes up by one, a cyanide step is needed (KCN on a halogenoalkane, or HCN with KCN on a carbonyl compound). Halogenoalkanes and alcohols are the key intermediates that connect most AS routes. For every step give the reagent, conditions and type of reaction (substitution, addition, elimination, oxidation, reduction, hydrolysis, condensation), and remember that the overall yield is the product of the step yields.
Do not try to oxidise straight from an alkane or alkene to an acid at AS: go through the halogenoalkane or alcohol. Give conditions as well as reagents: NaOH(aq) gives an alcohol but NaOH in ethanol gives an alkene; distilling gives an aldehyde but reflux gives a carboxylic acid. Use KCN in ethanol on a halogenoalkane, but HCN with a KCN catalyst on a carbonyl. And the overall yield is the product of the step yields, not their average or the lowest one.