as a sapper build a totem near the battle. rebuild as soon as it gets destroyed or when it is at 50% health or lower and there is no fight going on at that time.

teleporter is only useful on some maps. if the spawn changes often, don't bother building one.

barrier is only slightly useful form my experience. damage skills make you more viable.

engage in the battle as much as you can! either in melee if it's not too dangerous or shoot at anything that is around... you need all the classpoints you can get for buckshot and flashbang.

flank the enemy and try to lure gunners out of their guns so you can hijack them. if the gunner gets out, make sure you don't stand too close to the gun so he directly lands in your traps. knock him dead fast if possible or get in the gun as soon as he leaves. both techniques work.
if he doesn't get out, you should be able to kill him with your prepared traps and some hits.

if you don't go flanking, make sure you protect your paladins.

Totems and TPs are the most important.
Teleports can single handily change the tide of a battle, and also gives you the most Class Points for your stronger abilities.
That enemy ice witch a problem? You need that steam hammer as quick as possible, and need enough CP coming in that you can place it again right after a zerker destorys it.

How can you ensure that?

Teleports. Every match you need them.

Barrier is not very important to me because it doesn't give me support points. However, barriers are very very very handy when you've got objects such as teleports, and steam hammers on the field. It's an extra coat of armour which can ensure those zerkers will be taken care of before they destroy your tools.

Later levels you find that even though you can melee, it better to stick with your gun. You get a lot more CP per shoot, and don't get your ass whooped so easily.
Build up that CP, support your team, drop traps, control the direction of the match.

You can carry a whole team by just support and direction alone. Take advantage of these powers.

Low level sapper can however just run out and beat anyone up, so do that too. xD

Just try to bucket shot any frost witch or sister of fire at low level. Until you get mortar ; )

Before lvl 10, you have very few skills but just with your totem (it's not just about support points, it also gives a energy regen buff ... zerk gonna love you), you should kill almost everyone, you can spam your rmb.

I just wish that barrier can't be jumped.

Never a good idea to spam your power attacks. That's a mistake that gets you killed often.

Hi

What is better arquebus or hammer? which prefer?
If you prefer a hammer, what skills for him?
If you prefer a gun, what skills for him?

I can not decide.

Pls advice.