a single ffd which i hope i never have to use in game and basic pain meds like ibuprofen and co-codamol also antihistamine, loperomide,
i also carry sachets of electrolyte replacement like dioralyte or the supermarket equivalent, this gets used A LOT
clean water for wound cleaning or if safe to do so eye wash, also for drinking with or without the electrolyte
i dont carry plasters any longer cos really, they just wernt getting used and anything that you might use a small plaster on can usually just be ignored ime
as others have said, training is the key here, have some and know your limits.
never been a medical professional but had a few in the family and close mates etc and they would remind me of an unfortunate saying in hospital emergency departments
"first aiders kill people"
so whenever i have been required to offer aid to someone i always kept that in mind