Hi,
Never really thought about this - I don't recall ever accidentally locking myself out of a switch, so you're possibly worryng too much.
The first thing I always do is setup a management VLAN (normally the default VLAN 1) that switches etc belong to, and make sure I can access the switch through that. If something goes wrong at that stage, you can just do a factory reset and try again.
I then add my other VLANs on top of that, never editing the configuration of that management VLAN.
It probably also depends on your switch - my only experience is with relatively cheap Netgears (GS724 and below), which possibly have less knobs to twiddle (and less ways for things to go wrong).
And to answer burakkucat, yes, the Firebricks (I have some FB2700s) have a similar "test" facility, and also ways (IIRC) to revert to earlier versions of the configuration.