Ok, I have a tendancy to date "odd" men they have all be very tall (DH is actually the shortest)
Suits are like anything other item to clothing different styles work for different shapes and they all made "standardised" in one way or anyother.
So you have a few options avoid them all together which would be a shame or learn some suit buying skills and then get alterations done (they can be done cheaply etc)
Trousers waist band should sit on or just below the belly button
Tourser cuffs should break (end) on the shoe mid way between the top of the shoe and the toe
Trouser cuff, should not in a good quality suit be cut striaght as the back of the cuff should rest just above the top of the sole of the shoe. This can make a cheaper suit look massively more expensive
A good tailour should charge in the region of 10gbp to alter a set of trousers cuffs
Jackets, you have high break and low break to start with
ok high break, the lapel should have a point on the outer edge above the nipple line and be quite narrow if your DP is small to athetic build this style would work well as there is not a lot of space between his shoulders. higher brakes look better on a lot of body shapes.
Ok, shoulder, you want the shoulder of the suit to be a LITTLE bigger than the actual shoulder line of the body but not a lot. In a s / build maybe the width a a finger no more. in a guy with build arms you want the shoulder width to so the the suit does not tuck back in and then buldge for the bicep.
Double breasted / single breasted. Most man will get more use and look better in single breasted.
Ok jacket lenght, this is very subjected, but in shorted men you want a jacket the is no longer then the hip line the last button should fall on / around the belly button (note the last button not the end of the suit). Taller men can carry edwadian styles and longer line jackets much easier (shorter men can do it but it more difficult to pull off.)
The jacket cuff, again very subjective, the most common look, will be to show in the region of 1inch of shirt cuff, again the break (end) should be just above the wrist. In S/A men you are going to want to show less cuff maybe 1/2 inch. HOWEVER, always make sure that a men raises his arms up to his shoulders to make a T shape, as we don´t want the cuff to rid up high on the arm. Now also look at the sleeves we don´t want any bunching in the sleeve of the jacket again a good tailour you are look at 10gbp to alter the sleeve lenght
Now the fit of the Jacket on the torso. You want the jacket to nip in at the back, this is more important in s/a men, as otherwise they look overwelmend. So look at the back from the side, does the jacket hang straight down? It should curve in from the shoulder to the small the back and back out again. NOT drastically
On the front you want to see a line that again goes in from the shoulder towards the waist and back out again (think very very very mild hour glass) BUT this the not common to all jacket shapes some jackets will be straight sided.
Last bit, the front of the jacket, when buttoned! There should not be massive amounts of lose fabric, the jacket should hold a staight line over the stomach and not bludge or gap.
Three piece suits are more tricky to wear but they are a nice alternative if you DH feels very uncomfortable in a jacket as he can take the jacket off and leave the waist coat on. I will happily explain about waist coats if you would like
SHOES, all men MUST take there shoes with them to try on a suit / for a tailoring, as this can effect the lenght of the break in the trousers etc
White shirts are tricky, but coloured tone on tone shirts and ties work really well, so a a tie and shirt in the same colour but in a different tone. This is an easy to wear look and will look ok if the man wants to take his jacket off.
Ties need to be in a good not, half windsor is a classic and honesly easy to do, it will make a cheaper tie look much more expensive. The tie should also end around the waist band on the trousers. This is so much easier in a shorter man, the tie should NOT stick out from the bottom of the jacket
Shirts, there are numerous styles of collar, but broading speaking S/A men will look better in a smaller style of collar possibly even cut away. Make sure the neck size is right, its really important to the over all look. So shirt collar should NOT gape, there should be a little space between neck and collar, the wrong collar size is the same as wearing the wrong bra size in women. A collar size to big will swamp both the man and the suit and a collar size to small will a be very uncomfortable an will leave men looking like their necks are bulging.
I hope that all makes sense? IF there is anything else you would like me to try and answer I will if I can