This image is of the Black Prince's armour from ~1370, to give an idea of what it would have looked like. This time period would be using plate, augmented by mail covering the joints, especially on the back of limbs as plate armour often didnt fully enclose the arms/legs at this point.
I'll break it down from inner layers to outer, starting with the torso.
Torso:
First item would be a linen shirt.
Over that would have been a gambeson. Something like this (note, padding on the legs wouldnt be worn with the style of armour I'm describing). The gambeson provided protection against blunt trauma, and was made by stitching multiple layers of linen together, or possibly quilted with cotton. Whilst this provided some protection by itself (and was commonly worn alone by people who couldnt afford mail), it also made the mail more effective, giving it padding to take some of the impact too.
Then would have been a mail hauberk. This is basically a long mail shirt that would be belted around the waist, so some of the weight would be on your waist, instead of all on your shoulders. This would probably be the heaviest piece of the armour, and it would be near-impossible to slash or cut through it with a sword. It's weakness was piercing blows however, which is where the next layer comes in. However, from 1325 onwards we know that mail sleeves existed. This would have looked like a short waistcoat with mail sleeves sewn in. These were used to save weight, as the breastplate would protect the torso, so the mail under would be redundant, and extra weight. Though a backplate would be needed as mail sleeves didnt protect the back like a hauberk would.
Now we have the breastplate. A large, curved piece of steel that ends at the waist. This is about as good as protection got in this era. A backplate might be worn, but some people opted not to, trusting to mail to protect their back, and not wanting the extra weight. The part of the armour that goes from the waist outwards over the top of the hips is called the fauld, and would be articulated to le the wearer sit down. [EDIT: Faulds werent common until around 1400, so I'll cross this bit out]
Over this would be a surcoat. A fabric garment that would protect the armour from the elemtns, and provide a way to display the kights lively, or coat of arms/colours.
Legs:
A pair of hosen would form the base, with the shoes being made from leather (possibly with studs on the bottom, it would depend on the terrain. Studs are good in muddier conditions, but not so good on stone)
Sabatons would cover the top of the shoe.
The next bit is the greaves, which would be fitted to the knights leg perfectly (these couldnt be mass produced easily, they had to contour to the wearers leg).
Above that we have the cuisse (or thigh armour) which would be suspended by attaching it to a belt in some cases (the downwards cone of the thigh means you cant have it just hang like the greaves do on the top of the calf muscle.
Head:
A common helmet for this time would be a bascinet or a great helm. This is a complex topic, so I'll link to a video by a guy called Ian LaSpina who was a channel called Knyght Errant, where he has done a very well researched and sourced video on the details of both of these helmets. Great Helm & Bascinet.
His main experience is with late 14th/early 15th century armour, which is just after the time period you're asking about, but he has gone indepth about armour before that. In those videos he shows historically accurate reproductions, the insides, and how they would be worn.
I'll also include throat protection in this part, something often overlooked in films/TV depections of armour. This would consist of the aventail on the helmet (see the above video), a short collar of mail that would be worn underneath the breastplate (with padding underneath), and a stop rib on the breastplate which deflected upwards glancing blows to the side of the neck. Knyght Errant also has an indepth video on this, see here.
Part 1
So, as I mentioned in my reply to the other answer, Germany is weird in armour history. Perhaps every country is weird if you look at it closely enough - I think one reason we don't hear about the eccentricities of Iberian armour is that English-language armour historians aren't studying it. But Germany stands out from its neighbors with a number of...oddities. Moreover, 1350 is a very interesting time in the history of armour - it is right on the watershed from plate armour being a supplement to mail (as it had been for a hundred years or so) to it being the primary form of armour (as it would decisively be in 1400 and arguably in 1375). So in addition to living through the black death and the Great Schism, our German knight is living in a period where armour is transforming in a rather fundamental way. We see this change reflected in a diversity of defenses - knights are depicted in varying combinations of mail and plate, and some forms of defense come into being and pass away in the mid 14th century!
I will confess I'm not a student of 14th century armour as much as 15th century armour. So I've based this answer on Edge and Paddock's general introductory text Arms and Armour of the Medieval Knight and on a survey of effigies from the Holy Roman Empire from 1340-1360. Unfortunately, I don't have a copy of Claude Blair's seminal European Armour 1066-1700 with me, so I can't consult that.
The armour of our knight is going to reflect both the kind of liminal time he lives in, and his own teutonic peculiarities. As I mentioned, he will being wearing mail and plate in a variety of possible combinations. As far as I can tell Germans are still wearing full mail shirts in 1350 - the English begin wearing purely supplemental mail in the third quarter of the 14th century, but they appear to be innovators in this regard. So our knight will have a full mail shirt, quite possibly with loose, half-length sleeves. He may have full mail chausses as well on his legs.
He will wear his plate armour either over this or (in the case of his upper arm armour) possibly -under- this (the layering of armour gets weird). If our knight is old fashioned the plate armour could consist only of a torso defense and armour for the knees and possibly hands. If he is cutting edge it could be nearly full plate armour.
