Power up phantom letting it get satellites and home position. (On level ground away from metals)
Then flip S1 several times to get it into compass cal mode. Do the compass dance with remote,keys, phones etc away from it.
Sit it back down and power up motors using CSC command on remote control. Take up to lower level hover and make sure it is keeping a good hover position, no TBE or erratic behaviors, before flying off and having fun.