I always use layers..it's the best..i always start off by adding like 7 layers at the begining
layer1 ground
layer2 skybox
layer3 road
layer4 german_base
layer5 american_base
layer6 german_doors
layer7 american_doors


With these's settings i use..it makes everything easy

the best way to do it is take turns.

One week you work on it, the next week you friend, or you could swap every 2 days, wot ever you want.

I worked on neuville with janova, when he got bored, i took over. and then when i got a bit bored or did not have much time, he took back over.

Its quite a good idea to work on maps with people because this way you dont get bored, when im working on maps on my own i get bored to quick and take like up to a months break.

Remember the rule of layers - It's easy to merge layers, but a PITA to separate the elements apart again.

On the subject of Layers... I have the following on my current project:

Clippings - any and all border "clip" brushes that keep layers within the boundaries of the map (including clips inside of treelines)

Portals - all of my portal brushes

Portal Structure - all structural brushes on the interior of the map that the portals hang off of

Ammo - ammo spawns (anti-tank rockets) and any decorations used to dress up the ammo spawns (such as crates or boxes)

BaseAssault - spawn points and the bases themselves
BaseUpper - any entities that vanish when the base has been breached
BaseLower - entities that are part of the base but that do not vanish when the base has been breached

BorderFoliage (a layer that I use when constructing my treelines, there are actually 4 layers)

Buildings (in a building-heavy map, I would have a BuildingLeft / BuildingRight pair of layers, or separate the buildings into an even finer manner)
BuildingDecorations (interior models inside the buildings)
- If I was testing out a new building design, I would put it in a BuildingX layer for a few revisions until we're happy with it.

BunkersAndTrenches (I separate these out from Buildings, although they could easily end up in the same layer as buildings)

CNQLocations - Locations of my Conquest objectives. Goes hand-in-glove with CNQSpawnsAttackers and CNQSpawnsDefender layers.

FoliageBushes - all bushes
FoliageDeadTrees - trees that are scripted to fall over when damaged
FoliageLowerLeft, FoliageLowerRight, FoliageUpperLeft, FoliageUpperRight - the (4) map quadrants
FoliageSpruceTrees - all of my shorter spruce trees

HQ - HQ objective locations

Lights - Any lights on the map (these would be better if they were in the building / bunker layers)

RiverBank / RiverBankBlend - the two layers used to create my river
RiverWater - The "water" brushes on the bottom of my river
RiverBase - An underlying brush that prevents the players from falling through the water, even if I screw up the RiverBank layer

RoadBase - All of my road mesh
RoadDecoration - Things like hedgehogs and bridges or puddles

Skybox - natch
SkyboxCeiling - Useful to have on a 2nd layer, but not necessary
SkyboxMinefield - A minefield brush at the bottom of my skybox

SpawnsTDM - Any TDM gametype spawns

TerrainLeft / TerrainRight - Any terrain mesh that is left/right of my central river
TerrainLeftDecoration / TerrainRightDecoration - things like boulders, fences, ruined vehicles and other things that dress up the terrain but aren't associated with particular structures

Vehicles - all script_vehicle entities
Weapons - all script_vehicle entities that do not move (paks and mortars)

AlphaBlends - alpha texture meshes
AlphaBase - solid texture meshes that mix with the AlphaBlend layer