need some help, general guide?

[tylor]

It's worth seeding zones with potential escort (Daikara, Forest, Dreadfell, may be even Toknor, if possible) to lower levels.

[omero]

The down side to this - there is always a down side - item drops are also keyed to level of the dungeon.

True, but if making progress becomes an issue (and for me it still is, most of the times) then no item drops will compensate for having to deal with some of the "out of depth" things that can spawn in some of the critical areas.
Maybe I'll get less experience and poor quality items but at least I get to see further ahead in the game and have a chance to learn better tactics instead of being bashed yet another time and having to start over the same trite sequence of T1 zones again.

[Omega Blue]

The down side to this - there is always a down side - item drops are also keyed to level of the dungeon.

True, but if making progress becomes an issue (and for me it still is, most of the times) then no item drops will compensate for having to deal with some of the "out of depth" things that can spawn in some of the critical areas.
Maybe I'll get less experience and poor quality items but at least I get to see further ahead in the game and have a chance to learn better tactics instead of being bashed yet another time and having to start over the same trite sequence of T1 zones again.

I would say avoid the vaults until later on. Vaults are usually the only place where you get out of depth critters.