is there a preference for splice points?

I'm just about to make connections to my 1990 Eclipse GSX and I'm wondering if I should always go to a connector to make connections (can be a LONG way.) Or is it normal to open harness legs and connect there.  Are there any standard guidelines regarding this?

Also, my Eclipse has the ETAC processor at the base of the passenger door front pillar.   I haven't spotted a good location for mounting the keyless entry controller (factory alarm is fine) so my current plan is to mount it and the needed two relays to a piece of strap steel and anchor that to the firewall behind and a little to the upper left of the clutch pedal (a bolt is already present.)  Are there other locations I should consider?  Also, (related to my first question) is it preferred to run into the door to pick up the needed switch sensors at a connector, or the far side ETAC, or neither?

Thanks!

Splices can be made anywhere, but typically not within 2-3 inches of a connector (if your splice fails or needs to be undone you need to have enough wire on the connector to make a new connection).

Diodes are only used in special circumstances - typically only starter kill in a car.

Thanks!  I ended up installing all my splices near connectors and went to the ETAC instead of opening up the door.    I know I violated the 2" to 3" rule with my ignition battery splice, but at least I'm certain of not having to undo it :)!  I think the others were all at least two inches.

As long as I'm not inviting early failure by not using diodes, that's fine by me.  Thanks again :)!