This issue comes up a lot and so many different people have their own way of addressing it.
I work with young babies and I see so many parents making up bottles with cold sterile water because they genuinely don't realise that formula has to be added to hot water. It is the heat of the water that sterilises the powder yet some people seem to think that as long as the water is sterile then its fine to add powder to it.
At work we are very rigid about the guidelines of making up formula in that we boil the kettle, pour the required amount of boiling water into the bottle, wait for 15 minutes and then add the formula to ensure it's being added to water at the correct temperature to sterilise it. We then give the bottle to the parents in a jug of cold water so they can then cool it to the temperature of their choice.
I know some people use the technique of using half boiled and half pre-boiled water to make a bottle, I.e add 6 scoops of powder to 3oz of boiling water to sterilise the powder and then add another 3oz of cool boiled water to make up the bottle to the correct volume and it be at room temperature but we are discouraged from doing this. One of the main reasons we are told not to do this is because adding powder to boiling hot water can damage some of the ingredients (possibly the proteins) because of it being exposed to such extreme heat though I'm not sure how true this is to be honest, I haven't really ever looked into it.
A poster above mentioned one lady mixing 3oz of boiling water and 3oz of pre-boiled water together first and then adding the powder, but I imagine this would mean the powder isn't being added to hot enough water to kill the bacteria?
I suppose the safest way to make up bottles for going out is to have a flask of boiling water and a pot of pre-measured formula and just prepare the bottle when it's needed? I always thought that FF babies were on pretty good feeding routines so would be easy enough to predict when their next bottle was due and start preparing it 15 minutes before hand? I say this with no personal experience of a FF baby though 
One thing I would be interested to know for the purpose of work is can bottles be reheated? I read on here of people making up bottles, popping them in the fridge and then warming them up again when needed whereas at work we're always told it's a big no-no and that once a feed has been made up, once it has cooled it cannot be heated up again. We are also told that a formula feed must be consumed within an hour of it being made up and then it must be discarded due to bacteria starting to be produced within the milk. Is this a general rule most parents know about as some parents at work look amazed/shocked when I go to dispose of milk bottles that have been sat around for over an hour and tell them I will bring them a fresh one.
I also come across some parents who ask for a bottle of milk but then half an hour later say they offered it to the baby but he was really fussy so they stopped trying but then ask me to re-heat because baby now wants it - is this safe? We always tell parents we can't do that and will make them a fresh bottle up but the fact that they're asking us to do it implies it's normal practice for them?
I always see comments on here about how there should be education about formula feeding for new parents prior to babies arriving and I completely ageee because it sounds like a total minefield of different people doing different things 