Here's a generic install guideline:

1. Install the game and any applicable patches.

2. Install any fixpacks (tweaks come later, AFTER content mods).

3. Install any worldmap mods now, BEFORE installing mods that add areas. Some readmes state that worldmap mods can be installed at any time. But I have always had the worldmap mod not recognize some area-adding mods if I install it later. It's a real pisser to get to a mod's "trigger" point (and sometimes the mods don't trigger till you've unlocked Baldurs Gate!!) and have no map point to go to. So you have to start CLUAing yourself to the new areas...it's a drag.

4. Install content mods. The big quest mods and the smaller ones like the Herbal store.

5. Install the Tweakpacks. The reason you install tweaks now is so items/stores/etc. installed by the content mods get tweaked too!

6. Install the Widescreen mod. If you are going to use any GUI mods, install them BEFORE the Widescreen mod.