Time series analysis

You are new to time series model 

what are the top 5 things you need to know.

1. check whether the data imported has date in the type of date. A very important step as most of the time it could not be.
2. There are chances that the dd mm yy  is not read in the same pattern. fix it.
3. know how to group data /aggregate data weekly,monthly ,seasonal etc 
4. Sort data according to time, latest first, oldest first, etc
5. plot graph with different series in same x axis.