A mannequin makes it much easier to work on any clothing project.
That said, I find those adjustable dress forms with the little dials to be pretty aggravating. They're fiddly to adjust, and then when you do get them adjusted, you have gaps at the CF, the CB, and the sides - just where you want to pin! They're also only matched to the person in overall dimension, but not distribution of that dimension. For example, if the chest-to-shoulder ratio doesn't match the mannequin's, there's not much you can do about it.
If you don't have the money for one of the professional, Wolf-style forms like Mrs. Peebles mentioned (and most of us don't), I would recommend either making a duct-tape dummy or getting a simple one-size mannequin and padding it up to your dimensions. Something like this:http://www.mannequinhub.com/mannequin-dress-forms/male-dress-forms.html
"Pinnable" mannequins are even nicer, if the measurements are close to yours. Regular dress forms can be pinned to, of course, but only through the fabric cover. Pinnable forms you can poke a pin straight down into.
I can't believe how cheap these have gotten, BTW!