well first off you could be a knight from a noble family which would mean that you would have received training in warfare tactics and weapons.
that being done you needed armor, chain mail, a shield painted with your heraldic family crest, under shirts to go under your armor a leather or heavy linen cap to go under your chain mail hood and helmet, usually a horse was also required. you would need your everyday supplies like eating and cooking utensils, weapons- sword , lance, mace, war hammer. you would also need a bedroll and a tent and probably several attendants to help transport and set up everything.
if you were a common foot soldier you may or may not have pieces of plate armor- you may have had simply a chain mail shirt or a brigandine (canvas shirt with steel plates attached to it) a simple helmet without a face shield. depending on what type of foot soldier you were you could either carry a longbow and a generous supply of arrows, a short sword to protect you when the bow was not in use. a long lance, a sword, a dagger , possibly a small shield, you would also have a simple pack for your sleeping supplies and eating and cooking utensils some way of making fire- most likely a striker and flint, possibly a spare pair of shoes.
Actually all u needed was a weapon and a red cross that showed u were making the journey in christs name and that was it. This is why so many people went on the crusades: because it could be used as a penace for anyone according to the pope
Armor; sword ,training ,know how to kill and fight, like your king enough to die for him.