When entering a flooded basement you should turn off all electricity and gas or fuel valves. You should then check the outside walls for structural damages or cave-ins etc. Let some fresh air into the basement via doors or windows, take a note of any damages for insurance purposes and try to get video or photographic evidence.
When pumping do not use an electric pump powered by your own electric system and your gas pump should be from an outside line. Water should not be pumped too quickly as the walls may be pushed up, so remove the water in stages to prevent further structural damages.
When cleaning make sure you remove soaked and contaminated items and place them in garbage bags, whilst doing so ensure that you are wearing appropriate protection in the form of gloves or any other protective clothing needed. After the water has been pumped out you should remove any debris or mud from floors before they are dry. If the walls can be salvaged then remove the dirt and sanitize if needed before drying, turning up the heat or using a dehumidifier will speed up the drying process.
Any serious repairs should be done as soon as possible but if they are minor immediate action is not necessary. You could encounter structural problems like buckled walls, settled floors, heaved floors etc. Settled walls or floors are indicated by vertical cracks either in small areas or throughout the whole structure. Specialised equipment will be needed for these repairs. If the floor has not returned to its original level or is badly cracked then a new floor is needed.