How do I boost my marks in an extended answer question based on a source?

Let’s take a look at an example: Using figure 2, examine how a spit has been formed by physical processes working together. (8 marks). 4 marks are awarded for addressing the command word: Examine. This means to break down the process in to a logical and linked step by step sequence. Try and include key terms if you can, such as longshore drift, as well as linking words. The other 4 marks are for providing evidence from the figure. This doesn’t mean a simple description ‘there is a spit’. You need to convince the examiner that you’ve looked at the source, so try to use the scale, movement arrows, compass directions and anything else in the key where relevant. To make your answer flow, you’ll need to write this evidence within the explanation. In my model answer I’ll make this clear by putting the evidence in brackets: Due to the (south-westerly) prevailing wind, the wave swash is at an angle to the coast. The backwash is at 90o to the coast because of the impact of gravity, leading to a zig-zag movement of sediment along the coast. This means that longshore drift occurs (from west to east). A sudden change in the direction of the coastline leads to an increase in friction on the waves and therefore deposition of sediment. Over time, this sediment deposit builds up and extends (for over 10km) across the estuary, with salt marshes forming in the sheltered space (behind the spit). The (faster, north to south) estuary flow limits further growth of the spit because of its currents and deeper water, meaning that the spit will not extend to the next stretch of coastline and form a bar. Also, a temporary change in the prevailing wind direction, causes the spit to curve (towards the mouth of the river estuary).