my father and i do ok when one cuts and the other pushes with the tractor. ive also done that love by myself, kinda scary and not osha reccomended!
here are the steps
LOW gear, put the bucket against the tree and let the tires just try to spin, set parking brake. cut tree, leave lots of hinge, get back on tractor, LOW gear, release clutch to friction point, then release parking brake so it doesnt roll back.
or
put bucket against tree and push down with the loader arms til the front wheels come off the ground. then cut the tree and let duck when the bucket falls on your head. (sometimes im a dum bass)