Actually, what you need to do is be in the habit of smoking up before you get spotted (can't always pull it off, but you need to practice it). Much harder to hit a ship hiding in smoke that you never even saw than to hit one whose position is very easy to judge because they were just spotted.
If you are unexpectedly spotted in the RN cruisers and enemies are likely to be shooting at you soon don't slow down and smoke, it's already too late and you'll just make an easier target while you wait for the smoke to hide you. Better to angle away and head for concealment or cover, make yourself as hard to hit as possible. Just because you have smoke doesn't mean it's always the best way to protect your ship, all the things that work for other cruisers work for you too.