When was the last time you had a look at the Highway Code? I'm betting it's been a while. Start by taking a look through the rules for cyclists. There's an overview section which will literally take you 5 minutes to read it. If you're thinking about riding on the road, you need to learn the rules.
Don't be afraid to use the roads as you should—the recommended positioning is about 1 metre away from the kerb. This should help you avoid all of the scuzz in the gutter while allowing cars to pass safely. If you're approaching a place where it would be dangerous for car to try and overtake you then by all means take the "primary position" in the central section of the road. If a driver gets annoyed, let them deal with it, you're saving them from potentially d ealing with much more grief if they hit a cyclist. We find it's best to remember that everyone is human, and to treat each other with courtesy regardless of whether they're in a car or on a bike. It's best not to be a dick and ride 2-a-breast (yes, it's allowed) on fast roads unless you're looking to annoy drivers. Use cycle paths when available; if there's a dedicated cycle path then it helps everyone to use it.
Check behind frequently to ensure you're aware of your surroundings and to alert drivers of the fact too. Always look behind before clearly communicating your intentions with hand signals, it may not be safe to change path so don't communicate if you're not going to follow it—check first!
Make eye contact wherever you can so that drivers, pedestrians and other cyclists are actively aware of you. Keep an eye on the drivers actions inside their vehicle to be as prepared as you can for what they might do.
If you can't see the mirrors, they can't see you. Don't travel up the inside of large vehicles to try and save a few seconds, it's much safer to wait behind, in view. Accidents occur when cyclists sit in blind spots.
If you can see movement in a car at the side of the road then assume that a door might open; check your surroundings and see if there is room to move if it were to happen. If you're not sure if you have been spotted, slow down. The same goes with pedestrians, if someone is approaching the road while on the phone or with headphones on then assume they're distracted and might step into the road without seeing you. Prepare for how you might react to avoid accident.
If I told you to stop wearing headphones you wouldn't listen anyway, but you sure as hell shouldn't be wearing noise cancelling headphones or deep in-ear buds. You need to be able to hear your surroundings louder than anything else.
Serious accidents and fatalities often happen at junctions. Don't gamble on amber, and definitely don't run a red.
The best way to handle a junction is to arrive in the middle of your lane, regardless of whether you are continuing straight or turning left or right. This prevents traffic from risking dangerous overtakes. If in doubt, wait it out.
British Cycling have a comprehensive guide on filtering traffic, but there are a few key takeaways.