Proper form is key. I'd say getting a bow with the proper draw length is first priority. Working from 50 to 100 should be fairly quick depending on your size, age, and general physique. If you have the time and skills I'd say make two or three bows with draw weights increasing to your goal. If you wish to go above 100 pounds then the increments will probably be smaller. The heavier you go the harder it gets.
i agree, once you get over 100-130 a pound has alot more significance as far as difficulty, but as far as how to get there, build up in increments and make sure you have a good technique so you don't hurt yourself,
by the way, do as i say not as i do, i went from 50-100 with one bow, my shoulders paid for it or the next few weeks , luckily i was used to heavy weight lifting so it wasn't worse than that
, dot underestimate what a heavy bow can do to your shoulders, also one last thing, WEAR AN ARM GUARD, i didnt when i was first starting and lets just say the inside of my left arm whent from white to red in a fraction of a second, then i was stupid enough to do it again
( i usually handle pain very well, but this time i almost dropped to the gound in pain
)
good luck,
noel
PS: once you go heavy you never go back so get ready