Order or rules is important, because it influences the amount of processing required for each packet. The most often used rules should be before rarely used ones. So in most cases, your very first rule should be the one for accepting established and related connections, because it will catch vast majority of packets. This is for rules in one chain.
Order of rules between different chains does not matter, because packet will only go into one (packet which gets in input chain won't ever go in forward or output, etc...). So you can mix it together (input, forward, forward, output, input, forward, output) but I think it's more clear when you keep rules for individual chains together (forward, forward, forward, input, input, output, output).
People who quote full posts should be spanked with ethernet cable. Some exceptions for multi-topic threads may apply.