One thing that can make it a little bit safer to do yourself, if you have a tractor and loader, or a skid steer, just lift the bucket up above you and slightly push the tree in the direction you want it to fall, then stand under the bucket while cutting. It shields your head of widow makers. I have done that several times, plus it helps in making sure the tree goes where you want it.
well I won't call this any safer, if working alone, , as a fact this would be even more dangerous,
one should NEVER get out of a front access skid steer with the bucket raised, its a major NO NO !
people have been killed doing so!
even with a helper to operate the tractor/skid steer, standing under a bucket is never advice by any safety stand point!
a better idea might be to cut part way and then PUSH things over with a loader bucket
but watch when doing this, as many times tree's that fall kick back up and can bounce back at a operator(more dangerous in skid steer with an open door, and then other flaw is, when things are NOT on level ground, operating at an angle and a raised bucket can have gravity issue's that can make you tip over
again, NOT saying this stuff cannot be done, just saying, there are ricks to doing them, just some advice and info!
another option if you have the equipment might be pulling tree's down, using some snatch blocks you can have a machine safely out of drop zone, hinge cut and have someone pull a little and things will fall as you want and should anything get a little hung up, again, a tug on things can pull them down!'
I know not everyone has things for doing this, but another option if worried about just cutting them alone!