Acknowledge lane discipline, and give other drivers plenty of warning of your intentions. That means using the mirrors and signalling clearly.
When joining the motorway from the slip road, remember that the double white lines at the junction mean give way - you can't just force your way into the moving traffic. Adjust your speed so you can slot safely into the traffic.
If you need to rejoin the motorway from the hard shoulder, build up speed before attempting to move into the main carriageway again.
When you're planning to leave the motorway, make sure you are in the first lane in good time to exit safely without forcing others to take evasive action.
Plan ahead. For example, if there are lorries in front of you and they are likely to change lanes, it's useful to have an escape route. This is important with foreign left-hand-drive lorries, because the driver is less likely to see you.