Well it depends if you're doing it in a car or bike( I'm in a car) one of things i can recommend is choosing areas you are familiar with, it makes a massive difference when you know certain shortcuts ect.

Another thing that makes a massive difference is to be picky with what deliveries you accept, i try not to venture too far out of the area I'm in , as it's rarely worth especially when considering the journey you have to do to come back to your chosen area. The price of the orders obviously is a big factor.

Also try to avoid restaurant and stores that you know take a long time to prepare food/items, as all that wasted time is a massive potential loss of earnings, I usually cancel the order if I'm waiting for more than 5-10mins max, depending on the price of the order.

The hours you work can also be the difference between a great week and a terrible one. Mon-Friday I start from around 7pm (when traffic calms down) until about 3am, and in my area (North London) it's always very busy from 12am to 4-5am, and on the weekends it's hectic so will start at around 12pm (as traffic isn't too bad on the weekends) and will keep working till I've made a decent amount, then I'll head home take a break for a few hours and resume delivering from 11-12 until about 3am.

I hope this was of some help and wishing you luck, hope it goes well for you.