Not caring for their e-bike.
Your e-bike needs the same love and care than other bikes such as an MTB or a road bike. Regular cleaning is necessary especially the chain and the cassette. Take paraffin or dishwashing liquid and apply it with a paint brush. Do not forget to lubricate your chain. Use a special chain lub or in an emergency WD40. Your e-bike deserves your attention.
Not servicing the e-bike
Never mind how often you use your e-bike, you need to service or get it serviced from time to time. If you cannot do this yourself, take it to the local bike shop to get this done. A ball park indication is to do so once a year.
Let the battery run flat
If you either ride the bike till the battery is flat or leave it for a period uncharged., you need to know you are reducing the life span of your battery. Always have some charge in the battery. If you are not going to use the e-bike for some time, charge the battery about 60% of capacity.
Not getting anti-puncture liquid
Using anti-puncture liquid in your tyres or tubes, is a common practice amongst fun riders as well as professionals. It makes so much sense. Your do not want to sit with a puncture whilst others are having fun. It is cheap and easy to apply it yourself. Buy it from your local bike store.
Not getting a proper bike set-up
We see many riders (of any type bike), that has the incorrect bike set-up. The saddle is either to high or too low or the handlebars are not the correct height or length. To me the saddle is the most important set-up that needs to be correct. You can jump onto YouTube for some pointers or the bike shop can do it for you.