Place FOB in a spot that can be easily defended, granted you have the man power and they are watching 360 degrees of your FOB. The build range on FOB is 50m, which is pretty far this is the same distance as Rally point/FOB denial if the enemy is near. So the further out you put the emplacements the better, given your teammates defend those area's appose to just camping the 10m around the FOB. I cant stress thiss enough 50m needs to be used to its full extent as much as you can, this will give your team a fighting chance with plenty of places to take cover under a heavy assault.
If your team is stationed at these fortifications, I repeat- this will not allow the enemy to place rally points close to your FOB, giving your TEAM more time to react to enemy assault.
Establishing a decent size perimeter is key to not being overwhelmed by one enemy who can pretty much pin down a whole team if team is stuck in a small area.
With this said i will give a few examples of places to throw down sandbags so your FOB does not get overhelmed easily.
Blue=FOB Green= Good sandbags Red=Bad sandbags
(Red does not directly mean dont put sand bags there, it just means you want to focus on establishing the perimiter so TEAM can get in and out of FOB with out taking instant fire its easy to get stuck in a FOB if snipers are watching every exit, this is why its crucial to establish that perimeter.) Note these are not directly the best places to build for all circumstances. SL should be able to adapt to map side, point route, enemy flanks etc. pics are just to show you dont want to lock up the compounds.
First guide figured id keep i short and sweet, ill try to update it into full on FOB guide, when i get more free time.
If i had a nickel for every time i said "I need one shovel"