First off, buy yourself some wrenches made for this, or at a bare minimum, some snapon wrenches with the polished jaws. I had a set of craftsman crows feet that are polished and those worked really well also. If you do not use these methods, you will scratch the crap out of them. IMO, if they are scratched they look like hell. Dont use a crescent wrench wrapped with tape. Doesn't work. Jaws will cut through tape-ask me how I know. You also want the soft aluminum jaws for your vice. I did not have them, so I took an old leather belt and cut it up and wrapped fittings in it and locked them in the vice-worked well.
To cut: I tape the hose really well with some duct tape. split the difference with the tape. Then, cut with a die grinder and then be sure to (for fuel system hose) blow the hose out.
Assembly: Carefully pull the tape off. Insert the hose into the hose end fitting. Make sure the hose doesn't fray, if it does, use a small screw driver to push it into the fitting. Its a tight fit, but you should be able to do this part with your hands. You can look through the threaded end of the fitting to see when the hose is all the way in. It doesn't have to go all the way, but get it close. Now re-tape the hose at the base of the hose end. This will tell you if the next step will push the hose out of the fitting or if the assembly was successful.
Now use some motor oil or other lube(I used some bike chain lube) and spread it on the threads of the fitting. Insert into hose through hose end and start threading by hand. Make sure all threads are clean. Lock the hose end in the vice with teh hose end sticking out just a touch( eighth inch or so) and start turning the fitting with the wrench until they are close and line up the flats(looks nice). Dont get greedy with the flats. If they are close you are good. If you go to far you will break the fitting. Get them close. They dont need to touch. Make sure the assembly didn't push the hose out of the house end and you are good. Remove tape and voila.
On all my hoses< i did one end at a time. Assemble, then check fit to get a good measurement on the total length, then cut and assemble second side.
Here is a shot during my assembly. Have fun. Take your time, measure 3 times, cut once.