Having a Plan B is a good idea. Having a Plan F might be self-sabotage.
Don’t have too many contingency plans.
It can be tempting to spin out many follow-up plans, in the form of “And if A doesn’t work, I’ll try B, and if B doesn’t work I’ll try C, and if C doesn’t work…” and let them keep spinning ad infinitum.
The problem becomes that if you’ve got too many of these nets ready to catch you when you fall, you will be tempted to put too little attention on trying to succeed with Plan A.
Yes, have contingencies. But too many and you might not ever reach your goal.