Playful imitation stage (9-18 months)
If your baby has been wearing disposable nappies exclusively to this point they may have lost a bit of their bodily awareness or may have some trouble releasing their pee or poo in a set position (like sitting on a potty), and may even show strong attachment to their nappies (actually waiting for one to be put on before going). Respect this when guiding them, and take your time, and spend lots of time talking to them - and using sign language if you want - while you're observing or practicing. Also, swapping to cloth nappies would be very helpful now for them to experience that wetness feeling again more often.
At around one year of age babies are able to learn more complex sequences so if you offer consistently at routine times they will learn to anticipate these opportunities more than before. They are also much more mobile and clearer communicators, which can be helpful for others that may them take to the toilet too. The fact they also have bigger bladders and can go longer between pees is very useful if you've been practicing for a while, and you could consider moving to training pants to start incorporating that pull-down and pull-up action.
You can use your toddlers enthusiasm, curiosity and love of imitation to your advantage when leading their learning. They love being involved in the whole ritual and will want to help with wiping, putting paper in the toilet, flushing, washing hands afterwards. Dumping the contents of a potty in the toilet will also teach them the connection with the pee/poo and the toilet. Take advantage of this strong developmental drive to imitate you by applying an open door policy when you go to the toilet. Talk about the process step by step. Ask if someone else will do the same for them. Eventually, toddlers will enjoy taking their toys through the process, cueing them on their potty. You may like to get a potty-themed children's book to read with them. Learning through play works really well - keep the idea of pottying as fun as possible!
Positions that work well for standing/walking babies
When your baby has started pulling themselves up on things and can stand comfortably for a few seconds you may find that for a short while they want to stand all the time, including to pee. If you aren't to worried about the chance of splash (e.g. by standing in the tub, sink or over a toilet or outside) it can be a fun way to mix it up; angling slightly forward can help minimise getting their feet wet, even for girls. Once the initial fascination has worn off most toileting will be back in a sitting squat or the back or cradle hold.
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Clothing tips for rolling/crawling babies
Long or short sleeve shirts, or singlets, paired with a nappy and legwarmers works really well. If you have open-crotch leggings or chaps with a good waist-band they can be your nappy belt, keeping legs warm at the same time. Sleep-gowns with nappies are great for night-time instead of messing with onesies or sleeping-bags. A prefold or muslin cloth tucked into a nappy belt or chaps may come loose as they crawl if they're very active, so cloth nappies over chaps is a safer option.
Clothing tips for standing/walking babies
Long or short sleeve shirts, or singlets, paired with a nappy and legwarmers still works well, but the benefit with a baby that can stand is that removing pull-ups/training pants becomes much easier than if they're sitting or held. If you're open to using no back-up for a while during the day you could try split pants; any squat opens the pants for a quick offer. Walking also makes wearing dresses much easier, which is the fastest-possible access and reduces the need to wear pants over the back-up.