Start with geography
Dubai is not one compact sightseeing district
Burj Khalifa, Dubai Marina, Palm Jumeirah, JBR and Old Dubai are not all clustered together. Treating the city as one small centre can lead to an itinerary with unnecessary travel.
A better approach is to understand what each area offers, group nearby places together and decide which neighbourhoods deserve the most time based on your interests, trip length and accommodation base.
You do not need to stay in every area you visit. Choose one base that fits your trip, then explore the rest of Dubai from there.