my starting character is a Geomancer and I took the spider at the start. It greatly helps. (Well in all RPG game I have at least one summoner, so I'm used to this gameplay as well).
Lots of things are random in this game.
Most scrolls are loots so you must be lucky enough to find one.
You can also craft scrolls. Here again luck enters into the game as you do not control which spell will appear on the paper (you control the base element, not the spell).
As for skill books, as I read, merchants content is regenarted at level up so you should check the merchants at this time and buy the relevant skill book when you see it.
Lots of luck involved, but lots of possibilities too.
Note that summonings will not last for long (well my spider can resist around 3 turns though) so indeed you need lots of them.
As another tip: you can save during a battle. When things are going ok save and if something goes wrong, reload. You will be in pause state at loading right away.
Do not forget you can flee too. So when you kill one or more of the opponents, just flee (if you can), recover and come back.
For crafting, including enchantment, have a look here (search for "resistance"):http://www.larian.com/forums/ubbthreads.php?ubb=showflat&Number=524643#Post524643
Note that you need an essence, I have been told they are rare so it is maybe safer to keep them for later.