You have to be very alert and resposible when it comes to providing support because you dont have much time to react and handle the issues. Usually deadlines or SLAs are defined for each stage of the batch and if some issue comes up you have to show ur presence of mind in dealing with it depending on ur role ,whether ur the primar or secondary support person.
The next very important thing is proper and on time communication to the higher managment or with other Downstream teams who are resposible for any Business Impact if any issue occurs.
As Shirish mentioned the common errors are:
1. Late feeds from Upstream
2. Getting incorrect source file [old one]
3. Getting special characters/Duplicate recs in the file.
4. Environment Issues like Database down/hung or informatica repositories down/hung. etc