Capture is a much faster paced game than the other two. Balancing capturing and defending the capture points with making sure you have the augmentations and gear to do so makes things a little different from pushing on incursion or meltdown. From my experience the varelsi are the key to victory and the time it takes to get the shards for gear is too great to be worthwhile unless you already have 2 of the 3 objectives (much more so on Outback) So I would recommend a - healpower + shards per second item as your first item to help you get shards for your other items and structures.
Running round in a large group of 5 is intimidating but I have won several games where we would split up to ensure we could always have the other 2 objectives the other team weren’t currently pounding into dust. The most extreme example was losing on kills around 10 to 50 but still winning - easier on Temple because it takes longer to navigate to each objective.
On Outback, I may be mistaken but I believe the path to the left from each base is ever so slightly longer to their corresponding objectives, so if you want to contest this objective then you need a fast character (might be completely imagining it though just how I play)
Varelsi spawn 2 minutes into the game, but you don’t really need to know this because they are clearly marked on your minimap when they spawn. Ok Not exactly underhand but if you cap 2 objectives, you will be level 2. Defending the second objective from the capture point itself will give you 3 exp per second and is a nice boost early game while not putting you out of position. Being very close to lvl 3 before the first wave of varelsi spawn is the key. Varelsi give a small amount of exp for the kill and a Helix point so head over for varelsi almost lvl 3 and you can jump to lvl 5 for killing both varelsi at one camp while everyone else is lvl 2 - except the player that hit the other camp.
Pressing the advantage while you have your Ult before anyone is nice but controlling the map with teamwork is how you win.
Melee characters may have an advantage on paper, but building turrets around the capture points is an okish way to counter them because they can’t take them out while capping an objective - but this can be hard due to the lack of shards.