Hey Danial,
Nice first attempt, a few recomendations :
1) Get yourself a rattle can of Testors Dullcote. A final coat or two of this (thin coats) will remove that shine that seems to haunt us all :-)
2) Groundwork ,as already pointed out, the square on the circle base does look a little strange - continue this out to the edges. Also perhaps include a bush and or a log etc to add some intrest and cover for the SAS trooper.
3) Composition - a lone figure is always a hard one to pull off - spice it up a little with perhaps a map spread out next to him and a radio set - he looks like he could be acting as a FOO (arty spotter) and it would certainly spice up the vig.
Looking forward to seeing your progress with this,
Regards,
Andy.