Sometimes this one is not “hard” at all—it can be one of the quickest missions. Gold condition seems to be retaining at least 200 points at the end. 250 is very doable, usually, if this is a level 1 or 2 map.
Level 3 and higher can be more challenging: The Germans will have lots of units, including multiple mortars, covering the VPs from the outset.
The mission starts with the Germans’ holding 1 or 2 VPs, so (after a grace period of a minute or two) your point total starts dropping, and the Germans can be aggressive. You need to capture a VP asap, keep your squads alive, and do your best to keep that VP and keep at least one other VP from being under full German control. Eventually establish a solid defense of two VPs with a balance of anti-infantry (HMG, LMG, Rangers) and anti-vehicle (AT gun, schreck, bazooka-equipped Captain squad, Stuart, captured raketenwerfer, schreck-equipped Rangers) power. Munitions and fuel are relatively plentiful on this mission, so you can get a Stuart within a few minutes of the start. Also, you can get some points back for recapping German-held VPs—which is how you can end with a perfect score of 250.
Note that you start this mission with just one RE squad and must build out your force from there. At higher levels of difficulty the RE squads are good for nothing except backcapping or building bunkers away from German units.