Some times then stepping a mast the shrouds can get twisted up on the mast so that the wire is actually running up and then down. It is especially easy to get the forestay stuck if you have a furling jib. Taking pressure off a shroud can loosen it for gravity to straighten it before you even notice.
As stepping the mast solo. It is best to have your side shrouds fastened, point your boat at the water (while on the beach/shore) so the front of your boat is lower than the back, and then step your mast. Lift the mast from as close to the top as you can. Lifting near the base at the start is, well just don't. The further back, the less weight you lift and as the mast goes up, it just gets easier.
Gravity should hold your mast up along wit your side shrouds. If you have a bob on your mast, high winds might blow your mast down depending on angles.
With practice I've been able to lift my getaway's mast solo.
Check out the getaway mast raising thread. http://www.hobiecat.com/community/viewtopic.php?t=847