Where are you based? Are you racing / cruising?

If you mean you don't have a crew but will be at say an open - then I always find that the visitors at opens all tend to help each other... Don't be afraid to ask - you'll look stupid when you break your shiny new boat and someone says "If you'd said I'd have helped!"

There is no 100% safe way with the bermuden rig - its a bit big and so difficult. But most people attach the shrouds before stepping. If you put a longer tail on the forestay you should manage to loop it through the foredeck fitting before stepping - in which case it MAY be possible to stand the mast up vertically in the hull and the simply lift it up onto the step while keeping the tail of the forestay handy - then keep the tension on the forestay and move forward to secure it.

I'm about to try my new forestay which has an extra long tail and will run back to the mast to be (clam) cleated rather than tied. Thats similar to the ORIGINAL heron - it ran the forestay under the foredeck and back to a cleat. As I've just tanked the foredeck mine will run above deck next to my roller furling control line. But I'm dealing with a Gaff Rigged Heron so stepping single handed is a bit easier.