It is important to differentiate between points which primarily reflect combat potential and points which primarily reflect plot potential. Players are encouraged to pick a large amount of skills and to carefully consider how they want their character to be able to influence the setting. Points spent on non-combat skills will matter, and adventures will in many cases be tailored to consider the skills picked. Not every adventure will involve a fight, but most (if not all) adventures will involve skill checks where the course of the plot (and indeed the whole setting) hangs in the balance. No consequential decision will be determined by GM fiat when it would be more interesting to have the players use a skill.
Therefore, when perusing the point values I've used for NPCs, it is important to consider that I am using the same rules for them. When I run simulations where two NPCs are in conflict over a plot point, it is their skill levels and other stats which will determine how things go (for the most part, anyway). When the players must accomplish some non-combat agenda in the setting (think big: like influencing a whole town, or beating the bad guy to a specific location, or any other situation where the goals of the party are opposed to an NPC) it is the skills of both which will matter. As success rolls and contests (like combat) are all about cause and effect in a measured and probabilistic way (see p. 171 for the % breakdown regarding 3d6 outcomes and skill checks), it is hoped that through being consistent I can allow long-term plotlines to procedurally generate and resolve themselves throughout the course of the game without having to take too arbitrary a hand as story-teller. This almost scientific approach to building character statistics is one of the main selling points of the GURPS system, and it is embraced here.
So, if a player wants to get a good idea of what sorts of combat stats they should invest in then it would be best to examine the Bestiary, where are contained example "quick NPCs" with mostly combat-focused builds. A typical Street Thug, for example, is made up of about 55 points and is built for direct physical and social conflict. This should be helpful for deciding how "tough" your character needs to be in order to handle, say, being mugged; e.g. if you think your character should be able to take on a mugger and easily win then you should probably invest more than 55 points in combat-related areas (indeed, even the aforementioned stock NPC contains 18 points of non-combat skills included in that number).
For Mages: consider that investing 35 points in Unusual Background (Mage) and Magery 1, along with an IQ of 12 (40 points), only requires 20-ish points actually spent on magical spells to result in a character who can massively affect the setting and every single adventure with their "build". Considering potential Disadvantages which offset the cost, this leaves a lot of points left to be spent on non-spell skills, attributes, traits, etc.
Very few people in Nool practice magic full-time, and even fewer rise to the level of an archetypical fantasy wizard. Most magic-users in this setting use their spells to complement other abilities and skills. Players are welcome to make powerful wizards, but they will be outliers and capable of significantly altering the course of the game setting as events unfold. A character with, say, Magery 3 and Explosive Fireball-16 (who is willing to use it in a street brawl) would not only be one of the most accomplished mages in the land, but also be likely to upset the balance of politics and culture around them in the game. A likely outcome for that given example in most cities of Nool would be attempted detainment by the authorities, who would then send for experts to figure out how to deal with you.
Note that (with few exceptions) the cities of Nool have no laws against magic, but even among Mages there is a strong cultural taboo against using Magic to "get your way". Attitudes towards the supernatural have waxed and waned in the land over time, and the current balance is the result of having dealt with these issues before in the land of mythical, cultural memory. Even a "good" Mage who spends their life totally immersed in the study of the supernatural will harbor a cultural resentment towards the "wrong kind" of mage (represented as a boogeyman in the minds of most people). While very few citizens of Nool take issue with mages in general, nearly everyone takes issue with these boogeymen of lore, and the hallmark of such a mage (as every commoner raised on folk-tales will tell you) is that they are able and willing to use their magic directly and publicly in a destructive or coercive way (although in different words, perhaps).
It is taken for granted that mages exist, but most magic users are subtle out of necessity; blowing up muggers is likely to raise the ire of the public, the authorities, the criminal underground, and more discrete mages who resent the extra attention. Mages who draw attention to themselves risk drawing the interest of malevolent and benevolent forces alike, in any case. So, if a player wants to put all their points in flashy spells (hoping to blow away all opposition) then that is an option... but they should be prepared to be the center of a lot of attention which will quickly put them in situations that challenge their abilities more than the muggers they just blew up in public!
In practice, this means that the relative skill level of magic-using NPCs in Nool is low even if their IQ is high... Even talented individuals find it hard to study their craft in an organized way because of the inherent social, political, religious, and practical difficulties of building anything like a "wizard college". NPCs (and player characters) with even slightly higher relative skill values in spell skills (+2 or better) represent the most learned and capable mages in Nool, because there is no way to gain spell-casting knowledge short of figuring it out yourself or apprenticing to a more powerful mage (if you can find one). Because of this, talented loner mages tend to also be experts in Thaumatology.
See Mag Maekh for an example of a magic-user who would be considered typical of a "low level" but highly competent Mage in the Nool kingdom: she has only 16 points invested in spells which are best used with discretion, and her relative skill levels in them are mostly below 0. In spite of this she has points in Thaumatology, because she had to teach herself everything she knows. This is a good guideline for how a "low level" mage that makes sense in the setting could be built.