You get a lot of leeway when starting with a 12 month old - there is very little you can do wrong as long as you don't bore or frustrate your child.
Word size should be large - they recommend large on an A4 size sheet I believe though I managed with words 2cm high (so an "a" would be 2cm high and a "g" 4cm high because of the tail) This is slightly smaller than recommended.
Show words and then if you want to show pictures show them immediately after the word the picture corresponds to.
Use words your child will be interested in fort (like Mummy, Daddy, their name, an animal they particularly like, their favourite toy etc)
If you want to do the right brain thing then words should be shown very fast - only a second or so. I didn't worry with this.
Sets of five are usually recommended but again it varies from child to child (and parent to parent) - be careful to stop before your child is stops showing interest.
Good luck - play around with it and see what works for your child - remember they are heading for the toddler stage at 12 months (if your child is walking it becomes even harder) and you will have to adjust thiongs a lot to be able to keep showing them when they want to run away. There should be lots of ideas for keeping a bust toddler still seeing eth words.
Hi Tanikit,
You were saying 5 sets of cards but may I know when or how do I know to change to 2nd 5 sets? or it does not matter at all?