I know krtecek007 already posted about how hard the 1st level is and asked for tips. I just cleared the first sector of 6 enemies and it was tough but with a bit of patience, I got through it.
Now I see that the 2nd level is a guard house with 13 enemies! Wow, does anyone have any tips for this sector? I'm on Novice and this game is destroying me.

There's a few words from Leslie Nielsen that apply to both golf and JA:
Keep your head down. Keep your stupid head down. Keep your damn stupid head down.
Stay low, don't go out into the open without a good reason, and herd your enemies to you. Cover is your friend, and early on bodyshots are your best bet because of the low point cost for decent accuracy. Don't worry too much about trying to get perfect shots, just shoot for 50-75 percent or so. Also, JA is pretty randomized in terms of number of enemies, so there aren't really 'levels', just sectors.

JA 2:UB is not an easy game. Here are some tips:
CHARACTER
- when creating your character (btw it is possible to import one from the original JA 2) keep in mind that this character is probably the best you will have so take your time to think
- I would recommend you to read the manual to know what are the skills good for
- you probably won't need much points in medical, explosive, mechanic and strength skills
- on the other hand marksmanship, agility and if possible dexterity and wisdom should be high
TEAM MEMBERS
- for me it was always better to buy one or two really good members of AIM than to buy a lot of cheap and unskilled
- it is good to recruit for instance Lynx (marksmanship 99) or Shadow (camuflage and high skills)
- later you can buy some really cheap mercs to be used to carry ammo and guns from your sectors to the location of your main team
WEAPONS & ARMOUR
- choose wisely :-)
- you'll probably find a enough weapons in UB so you don't have to repair them much
- you should try to save ammo because it is better to have more than no :-)
- some types of ammo should be used only later in the game (like 4,7 mm or rocket rifle ammo)
- sniper rifles might be good for open areas especially if you have a skilled sniper (99 or 100 marksmanship), you are on a roof and you see the target... but if you have a good sniper you can even hit a target that is quite far
- in the end you will be probably using automatic weapons with burst fire
- it is possible to modify the weapons with sniper scopes, lasers, silencers etc.
- some attachments for weapons can be made with various items (steel pipes, aluminium rods, duct tape, springs etc.) some have to be found
- the best armour is spectra I think... you can also use something called "compound 18" to even improve it - don't use it on any other armour because it is rare!
COMBAT
- the position and number of enemies is quite random (but some places like the rooftops of bases are usually occupied by elite soldiers)
- try to move silently (silent mode is turned on with "z" key)
- aim (right click on target) and try not to loose too much ammo
- keep down (page down key)
- use cover (but be careful - sometimes the bullets can come through obstacles like trees or thin walls)
- hitting a moving target is more difficult
- sometimes it is good to use granades if the enemy already knows about you
- i have never been very successful with knives, fists etc. but some people say it is possible to finish the game using mainly these
- save
- try to aviod injuries (healing takes too long)
- sometimes the enemies are using energy consuming bullets so carry a field bottle or drugs to get more energy
MONEY
- if I remember it correctly, there was a possibility to sell things later in the game, but I'm not 100 % sure (i played it when it came out)
I think this might be all. There are some other things but they would probably spoil the game :-). Enjoy this great game :-)