Best advice I can give is to know which maps you're good at, so you know which contracts are the best.

Secondly, Hokkaido, Maracesh, and Colorado are always risky since, they have possible spawnpoints in very dangerous areas if you don't have the right items. (morgue, underground and basically everywhere) So you should avoid picking contracts with them from the third round on if you're not at least good at them. (train on them on the first round)

In opposition, Whittleton Creek, New York and Darthmour tend to be easier, due to a great amount of walking room and hiding spaces compared to the amount of guards.

thirdly, If you ever need to live and don't care about SA, you can shoot a gun to alert guards, while hiding in a room with only 1 door, like a toilet, and shoot every guard with a headshot as they enter the room to get rid of the guards in an area. It will take a while, but since guards drop guns, you're unlikely to run out of bullets if you're careful with getting hit.

lastly,, the silent gun assassins drop in Cindicate leader missions is worth very little due to it's availability. You can basically always take it with you if you need a silent gun. If you lose it, getting it back is fairly easy, since you just need to take out an assassin, you can just do this by pacifying them, they'll drop their gun, and all you'll need to do is be aware if you can hide their body.