I'm new to the game and I have a bad habit too just go with the lore of high magic all matches no matter what with my slain. So I wonder is there any tips of a good lore against three armies because these are the races i will be facing the most? these are the races: Deamons of chaos, Dark elves, Wood elves.
I'm biased towards light and Life, because both are far more supportive in nature, rather than offensive, which suits my saurus heavy army very well. Light especially seems really good against elves, because you effectiely render the initiative pointless if you get it off against elves. you suddenly strike at the same time, and take away their rerolls. As a nifty bonus, you cause additional hits against demons and undead, which is always nice. The net also works wonders against the low S elves, and since elves and deamons all have tons of ward saves, Banishment also works fairly well. Death is always a favorite, though, in terms of character sniping, and especially with daemmons, who have some really expensive characters in their princes, you can easily win hundreds of points with a single lucky Spirit Leech. You could consider Wandering Deliberations though. It is a pretty nifty thing to have, and gives you a ton of cheap spells, which makes miscasts rare, and dispel scrolls mostly useless, as you don't really have any expensive and powerful spells to dispel in the first place.
Prior to the 8th army book I would always run a life Slann for the toughness boosts and healing spells. However since the new book I have been using the High Magic Loremaster, for which HoG and WbW are the stand out spells for me. I've rarely ended up swapping out a spell either because I figure I will need the successful spell later or the throwaway spells I have cast are blocked. In my last game I finally used the WD Slann and found it really useful, admittedly it did mean that for the first turn or so I was casting pre-emptive buffs late game it gave me lots of options. I managed to snipe out an enemy caster using the death sig and the other damage spells were great for trying to run down the opponents dispel dice. I have a tournament later in the year so want to try the old standby of life magic again to see how it fares with the new book.
Light. Against the elves you have three buff spells which counter their advantages. Against Daemons you get the buffs and Exorcism. Filling most of your Core with Saurus (because they can use the buffs best) and taking some Salamanders (because they make up for Light having no nuke spell) should work well with Light
If you know who you will be figthing I would say it depends on the army you are fghting, but if you dont know definately go for HIGH MAGIC. And loremaster if you can! This gives you incredible flexibility