To identify core routes and ensure they are continuous and pleasant to use. Lots of high quality small facilities or treatments does not a network make. Journeys have to be feasible and pleasant from A to B (and plenty of cycle parking, preferably under cover at destinations). Limiting on street parking (my favoured trade off at the moment is 20mph or no on-street parking) also does a lot to improve the perception of travel as slower road users come less into conflict with larger ones.
Strategic approach: Identify the network and destinations. Identify the key bottlenecks. Identify the design standards to ensure that new development is connectable easily to the rest of the community. Identify who should be favoured in which areas.
Practical approach: treating key junctions that have been badly designed is a problem, is expensive and needs insightful and 'brave' traffic engineers.