Scouting is a bit of an Art. Its something that I used to be very good at but like most things, when you get out pf practice you start to be less effective. IMO when scouting you need to be both bold and reserved, the trick is when to use each of these traits.
The times i see scouts die the most are within the first 2 mins of the battle. Just when the opposite scouts are doing the same thing, just when the heavies are getting into position and just at the time when your most useless (in most cases) as a scout, as most of your team, especially Arty will not be ready.
Never stop when your spotted. Keep driving, fast, give you opponent the least profile possible to shot, dont turn side on unless you have cover. Use the terrain to your advantage.
The most important factor is simple. Stay alive. You cannot scout or help anyone when your dead. All you will do is serve to **** your team mates off because it means someone else, in a less suitable tank will need to pickup your role. It also means your own arty is less likely to survive the game.
Learning each map is crucial, knowing which booosh, or rock to hide behind and where you can be hit from is very important.
Have a plan, this is something we are getting better at, but Arty and Scouts need to know the plan so they can position accordingly.
Wait....Wait some more, hang out near the arty initially, for a couple of mins, let the game settle down. Its more advantageous for you to know the battlefeild before you set out. Wait for some red dots to apear. Once you know whats going on, you can see what tanks are where and then make a calculated guess where the others maybe.
You can also passive scout. Sit in your fav spot and dont move. Just light them up for your team mates.
Lastly, be opportunistic. If you see a tank on its last legs and you think you can take him then do so. Be smart though. Always try and get around the back. If you have an auto loader, try and track, then shoot. One thing I used to practice over and over was to fire on the move zoomed in. Its actually pretty difficult when your moving fast over bumpy terrain but there are skills that will help.
Oh and one more thing. Six sense is a must.