I am getting murdered in the Alien Base mission, even with Titan armor and Plasma Rifle. How do i get pass this stage?

Get a balanced team first. No need to rush into the alien base so fast, go do some missions and rack up experience. If alien alert becomes critical all over the world only jump in but by that time you are more than ready. You got titan armor so is impossible to die already, unless you do something crapstatic like running into a hall and aggro 3 squad mix with crysallids and mutons. Hell, I beat that mission with only carapace armor and laser rifles against muton berserkers too. Get some assault with lightning reflex to soak overwatch fire, use run and gun and double fire using plasma is sure kill. If your assault get caught in the open. Use SMOKE. Even if shit happens and they are standing in the open, a smoke will always save them from at least 2 shots. Sniper with buddysight is good, disabling shot against the heavies etc. I had 3 assault, one heavy, one sniper and one support for smoke .If not sure just use heavy and rip a hole everywhere with your rockets.

Stats:
Never used one medikit for the entire game.
Classic game.
Tutorial game.
Too lazy to savescum. So saved only once a mission or 10 turns once as quicksave.
Won the game before facing a battleship wtf. They dont send it early enough.

But I had to skip one terror mission. Laser weapons with carapce fighting at a highway road. Face 3 cyberdisc squad that throw plasma grenades non stop when the only cover is cars. lol. All civilians on the other side of the road with 2 crysallid squad infesting them. gg. Better loose one country than my precious squad.

Impossible to die to those suited snakes or sectoids. Poison is nothing unless youre unlucky and get a string of poison damage early in the mission. (I dont use medikit and on carapace armor so yeah)
If mutons can always wither them down and spread out in case they plasma grenade your face (but got titan armor and damage is jsut 5 so should be ok) unless youre unlucky get intimated and your panicked squad start shooting each other.
Berserkers can be kited.
Crysallid is a tougher nut and since you got titan, just unload the missile on their faces even if your scout is nearby.
Always have your sniper ready to disable the flying saucers, then kill them asap within those 2 turns. If aggro more than 2 squads be prepared to suicide your assaults, burn them through and hope you can kill them before they kill you (thats why I have 3 assaults). Priority towards melee units then ranged, smoke cant protect against melee damage.
Support smoke to protect the the suicide assault team.
Heavy is there to clear some shit in case they hide behind walls or need to be shredded.
If you reach the psionic sectoid at the end, sniper 1 headshot and one regular shot can get it to 3 HP, then run and stun him.
2 of my (assault and heavy) use Arc thrower. all the rest uses SCOPE. support use nanoweave since shes the scout. no grenades was used.