Wouldn't change what I did.
Ignore where everyone else is going (friendships change massively in Y7).
Visit every potential school your child has a chance of getting into.
Take Progress 8 and Ofsted with a pinch of salt - but do look at things like percentage getting 5+ in English & Maths, and if there is a cohort getting straight runs of 8s and 9s.
Look at the extra curricular offer.
Closest isn't always best.
Make sure the school is right for your child - just because it looks great on paper doesn't mean it will be in practice. No point picking the school with amazing sports if your child prefers art and chess.
Have a list of questions that are important to you and find a member of staff at every school and ask the same questions. You will learn a lot from that.
Do the school tours alone and then take DC to see the short-list. 10 year olds are swayed by the weirdest things and you don't want to hate a school and find they are fixated because the school canteen serves chips.
Start looking in Y5 if you have plenty of options and make a list of key dates - things like aptitude tests tend to happen in the September of Y6 and easy to miss the deadlines if you're not aware in advance.