All bitches are different some behaviour with change some soppy Angels, some little demons and others don't change.
There is no need for nappies or pads unless you wish to use them.
Don't walk her offlead and don't let her around male dogs. We personally don't walk when in season as my bitches would flag to a tree.
Bitches are in season an adverage of 3 weeks every 6-8months, it will start with red blood then go clear or straw coloured this is when she is ready to accept a male, the bleeding then starts again, some bitches will bleed red though out.
Some bitches will be so clean you won't wven know their in season without you having a good look at her vulva, others are very messy and again some you will notice a few spots.
If she's to be spayed (very good idea for health and because you don't know about seasons) let you vet know and make a note of to when she has come into season as most vets want to wait until a couple of months after a season to spay.
Also even if youdog is as big as a Leon little dogs will still try and bitches have been known to lay down to allow these small dogs acess.
Make sure you don't leave her unattened in the garden as not only May she try to escape makes may well get it, 6ft fence or not, dogs have been known to destroy doors/fences/ eat though dry wall and mate though metal fences.
If she does get caught there is an injection she can have bit like a morning after pill for dogs as she is way to young for a litter.
Also she could have a phantom pregnancy after a season don't encourage this if she does, she will try to hord "puppies" so teddy etc.
If her season is off colour and smells bad straight to the vets as she could have pyro which can kill if not treated fast enough.