1 Sleeves and pants. Your sleeves should be right over your round wrist bone, about 1.25 cm above your shirt cuff. The pants legs should have a single medium break in the front and the back part should fall where the top of the heel meets the leather of your shoe.
2 Armholes. If the armholes are a bit high and tight, they can be tailored to get you more room. But if the bottom of the arm opening is low and baggy, you should choose another size or cut.
3 Rollout. Most of suits are cut with a slightly sloped shoulder. That is why men with broader shoulders get an unattractive fabric roll that gathers where the collar and body meet. It should be removed by your tailor.
4 Middle part. When your jacket is buttoned, tug it away from your body: your should have about 5 cm of room. More than that would make you look like a box, and we are aiming for a defined waist.
5 "2.5 cm of magic". While you're standing with your arms on the side, curl your fingers to touch the bottom edge of your jacket: it should fall right between your first and second knuckle. If you want your suit to have a modern look, take out another 2.5 cm, but anything more than that would ruin your suit's proportions.