Other myths and misinformation that people fall for:
"only put down one school, then they will have to allocate you that school!" WRONG!. If the school you put cannot offer you a place under it'sa admissions criteria, you will simply get allocated a place which is left over once all the offers have been made. Probably miles away, in an unpopular school!
"Only put down schools you really want in your choices, they will have to give you one of them" WRONG! No, if you wouldn't be offered a place under the admissions criteria from any of the schools you will be allocated a left over place, as above. So make sure that you include at least one school that you do have a chance to get into.
"Some schools only offer you a place if you list them first as your first preference" WRONG!. The Equal Prefernce System (which is LAW in England) decrees that the schools never know where in the list you put them, and are not allowed to discriminate based on where people listed them. Put the school you would genuinely prefer most first and so on.
"If you get offered a school you don't like, decline the place, then they will have to find you a school you like" WRONG! The LA has an obligation to find you a school place. If you turn one down they have no further obligation. Accepting a place does not disadvantage you in any way in terms of being on waiting lists for any other schools - but it does mean you won't end up in an even less desirable school further away! If there is a local school that isn't your preference, but IS the only school you are likely to get offered, put it last on your preference list.
The LA will offer you the school which was highest on your list of prefernences that was able to offer you a place according to their admissions criteria. You will then automatically be placed on the waiting list for any schools higher up your preference list and be offered those places if they become available.
The admissions process is statutory. They don't sit round bartering about "oh this person will be happy with second choice so let's give their first prefernce place to Marge down the road because she has only put that school down and we don't want to upset her..."