Oh man, I love the start of the game, and here are my random ramblings about it.
First, as other have said you probably should turn off the Drassen counterattack - it's just too brutal for a new player. Just keep in mind you have to start a new game for this to take effect.
The game options when starting a new game are critical and you should set them to your preference. For example, the item progression speed determines the enemy equipment (and through that what you can loot from them). Setting this to slow or very slow (my preference) will make all early enemies (at least until after you take Drassen) carry only pistols and maybe a rare SMG. This makes the early game significantly easier as at least some of your men will have SMG-s, giving you the range advantage needed to rape them before they can shoot back. The (very) slow item progression (and Bobby Ray shop selection set to normal or great) is a great setting if you wish to play with enemy drop all on and don't wish to get swamped with good equipment from the start. With drop on you will never want for medkits again and you can sell all that useless junk the enemy drops to the locals for some minor cash through the sector inventory.
When you are designing your IMP, I suggest you take markmanship 70 - that way you will start the game with a 9mm SMG, ammo for which is dirt common. Taking more than that gives you a 10mm SMG - good luck finding more ammo for that one early on. Concentrate on your abilities and leave skills as low as you can - it's easier to raise them during the game. Put as many points as you can in wisdom, agility, dexterity, strength and health. Especially wisdom, as it dictates how fast your character gains experience (the same is true for all other mercs, which is why I recommend you hire Barry if you haven't already - high abilities, very high wisdom, dirt cheap, lockpicking, explosives). Forget extra levels, they will come soon enough with high wisdom. Also, take night ops trait - extra vision during night, extra hearing range and less sleep required? Awesome.
Early on JHP or Glaser ammo are absolute killers - many enemies don't carry any armor and even a single pistol round can kill them easily. Automatic fire from a 9mm SMG loaded with JHP or Glaser ammo can easily take out several enemies at once. That reminds me, you do now how to make aimed auto fire, right? If not, first switch to single round, aim as much as you can, then switch to burst or auto, select the number of bullets and let it rip. You can't put as much lead in the air that way, but it will be much more accurate. Also, try firing at their legs and let recoil work for you. Even enemies that you miss might get suppressed.
Unless you are playing with slow item progression, your early assaults shout be made during nighttime (your IMP has night ops, right?). That way it won't matter if the enemy has range advantage over you, as they must still get in the range of your guns to see you (if you are playing with slow item progression then you have the range advantage and night attacks work against you). Just take it slow, watch you flanks (pay attention to noises) and try to draw them towards you by firing a round - if your mercs have enough AP left you will get an interrupt and take them out as they come to you. Keep an eye on vision cones and safe squares (delete and end keys). Also, roof tops are your friends.
If you still find Drassen too difficult, as other have said there is no reason to head there immediately. My suggestion is San Mona - it's close, no enemies are there (though you might run into some on the way there), you can make some serious cash and there's a weapon shop where you might get some better weapons (what will be available to buy depends on the Bobby Ray setting).
