He's busy playing probably, so he's not going to want to put his coat on or put toys away. But he's got to learn that Mum & Dad are in charge and we can't always do what we would prefer to do.
So, firstly try to give a warning first - eg tell him he's got 5 minutes with this toy, then we're putting it away to go out. Or we're leaving the park in 5 minutes, what do you want to go on before we leave? He's then got the chance to get used to the idea rather than suddenly abandoning his game, at which its only natural for him to want to say no.
Then you need eye contact and to be sure he can hear you when you say he must stop what hes doing. Then when you tell him what he's to do, with a child as young as 2 you can turn any chore into a game that sounds more fun than whatever he's already doing.
With getting dressed you can guess at which arm he's going to put in his coat first (if he's in a contrary mood you might find he puts in on real quick just to prove your guesses wrong lol). When putting things away, you have a race to see who can put the most cars away, for example. Then when he's done, you get the chance to praise him - give him a hug and tell him how good he is at tidying up/how clever he is to get dressed so quickly by himself etc.
Eye contact is important, when you say "I want you to ..." your body language/facial expression and your tone of voice all contribute to getting the message across in a way he knows you mean it and he doesn't have a choice in the matter.
Good luck. Remember he's only 2 - he doesn't stand a chance of winning a battle of wills or intelligence against you. But he doesn't know that, you can't blame him for trying!