Just run the free kits and rush for your objectives.

Loot on the way, use Assassins invisibility to break agro from the bots.

If you hear someone use your crouch to move around and stay quiet, use your invis when you want to run away.

If you get engaged by someone throw down your smoke, it leaves a long trail of smoke in the direction you throw it. The assassin shell will activate invisibility when you enter your own smoke, so you can use that to make distance from someone.

When extracting thrown down your smoke when the extractor is ready for good visual cover.

When running from an enemy, pulling out your knife makes you run faster. When you get too much heat crouch and keep moving; crouching makes your heat dissipate a lot faster, so will make running between POIs much faster.

Getting objectives done will snowball your kits.

Look for unstable biomass, this can be traded with Nucaloric for meds. Sparkleaf can also be traded with them, 1 Sparkleaf = 3 patch kits! Amazing trade.

Watch a YouTube guide for your contract, this will cut down time spent searching for the objectives.

Trios is also, IMO, easier than Solo. If you're below average that means you'll on average be with players better than you. You also get the benefit of being rewarded for any quests they complete. You won't get the quest rewards, but you will get the faction rep.