First is to get Mage Man-power at the character disposal. How much and how to get such man power. Next is the Basic Security Strategy based on Common and Simple threats. Haven with its massive population growth (more than 2% per annum) and attracting many expats makes magical manpower something very complex.
Mages are Allies with Special Abilities, always count the +50% where applicable as a Patron or Ally.
Rules in Review
- The Rule of 16 (B349).
Powerful Mage Allies and Contacts
Mages as Contacts (M44)
Mage contacts is the first step to accessing opportunities and magical equipment. The higher the level, the more powerful the equipment available. You can say contact skill level cubed is the FP worth of Item the character can get. Reliability determines the default reaction score level with the character, at unreliable at Poor (B560; sells at +20%-50% "market" price), somewhat reliable at Neutral (at "market" price), Usually reliable at Good (at "market" price), and Completely Reliable at Very Good ( up to -20% discount of "market" price).
Retainer Fee. 10-20% Monthly earnings of a Mage contact can be the retainer fee. Retainer fee is the freedom to bug your mage contact without having to exchange favors every transaction.
Preventative Measures. Consulting with a Mage contact helps determine if there is someone out for you, if your plans are going to cause problems with other mages, and many other basic planning information gathering. This is the cheapest and smartest way to go about things: watch where you tread.
Mages as Allies
Powerful Familiars, Demonic and Undeath Companion, or Fate Bonded Allies can all help when it comes to Magical Counter measures. Of course only the Time they can allocate to the PCs can be dedicated in this way, so an Unsleeping companion can probably hold vigil 24/7.
Allies (unless unwilling ones) are automatically at the best reaction roll with the PC (the unwilling ones in helpfulness but not feelings). Note that these are relationships and when the character eats up a lot of time and expense of some of their allies, and the allies cannot afford it then they may feel responsible (depends if they have some code of honor or sense of duty) for that ally. Note that PCs who have these sense of duty tends to have more allies lolz.
Mages count as allies with Special Abilities. if it needed to be said.
Paying Mage Allies. Some allies require retainer fee, others are Part of the PC's business and get wages from the PC. Allies should not exist in a vacuum, and their financial involvement with the PCs point out their strong shared incentives.
Mages as Ally Group
Being a Patron to mages, has its advantages, particularly when getting the price of the manufactured goods and leaving a very small detectable footprint for Intelligence Gathering as to the Size and Strength of the Organization. Most organizations project power in order to create ambiguity regarding the resources at their disposal, part of the game theory. Powerful Entities with Mages are ambiguous in the threat they can present, and often create peaceful coexistence in this game-theory situation.
The price is there if you want to make them hirelings to make them more accessible, despite their lower Freq. The better their Freq-Appearance the more available they are to help.
Group of Adepts 24/7 FTE 2 (typical for the most most powerful Mages)
At least Wealth Status 4 characterAlly (Ally 50% of Mage's Point Value; Frequency: Often, x2; Supernatural +50%; Group x6; Dependent at 50% Point Value of the mage, Freq-6 -5) 
Group of Masters 24/7 FTE 2 (typical for the most most powerful Mages)
Typically Wealth Status 5 characterAlly (Ally 100% of Mage's Point Value 5cp; Frequency: Often, x2; Supernatural +50%; Group x6; Dependent at 100% Point Value of the mage, Freq-6 -1) 
Group of Masters 24/7 FTE 2 (typical for the most most powerful Mages)
Typically Wealth Status 5 characterAlly (Ally 100% of Mage's Point Value 5cp; Frequency: Often, x2; Supernatural +50%; Group x8; Dependent at 100% Point Value of the mage, Freq-6 -1) 
Third World Mages.the way mages are created in haven is a process of Indoctrination, Patronage, and the extensive use of Minds Reading/Search and culling out dissent. Mages who survive the culling process and pursue the industry are those that are mostly likely freelancers or quickly protect themselves by joining a Coven. In Haven the most common mage groups are CULTS, worshiping the persona of some immortal mage patron (pretty much the situation of baby boomer or taken to the extremes in Transhuman settings).
There are very few Masterless mages. Mages of independent personality and initiative, and not part of some Cult or Coven (typically they are a "Circle or Guild or Fellowship" where they are peers in pursuit of knowledge -- total nerds). These mages owe their training to other Masterless mages who are pretty much like historical Free Thinkers, who breed through knowledge being passed instead of Indoctrination. PC mages in my game are Masterless mages (they do have mentors but they are not "Patrons" but teachers), they are the minority that is both dangerous and fighting for ground to survive (if not to thrive).
They are important to note that these are the extremely rare, probably 1:1000 and poverty and ignorance doesn't help the demographics lolz. They are pretty competent compared to the Adepts of Cults and Covens, and have a real passion. Typically seen as good guys because they don't perform the typically exploitative process of indoctrination, but can be REAL JERKS (be prepared to be offended lolz).
Allies, Contacts, Hirelings
Allies and Contacts have a Freq of appearance. When its not constant, it is assumed they have responsibilities that take them away from the player's access (they need to make a living, and the PC is not the center of his/her world).
I've discussed mage "retainer" (based on my experience working with lawyers in our company and various consultants). Then there is actually hiring them, making them part of your monthly expenses, for a long period (like 2-3 years with periods of evaluations, and basic provisions that maintain performance and protect you as an employer). Even if they are hired, the PC must declare their job role. Assume the lack of access is the mage doing research, gossip, and study.
Mages are expensive but a whole market of them doesn't make them too expensive. Example is Killian who earns about $5,200 monthly for the HSS and on retainer for a year. He is a pregen for players who want to taken on challenge of playing a mage, but is still a hired member of HSS and does his job (with his brother Bill who has a great disposition to evaluate his performance to Thomas and Osman) particularly providing and maintaining scryguards for the team (he maintains one for Speedy, Osman, Fish, Thomas, Himself, and Sid; -6 to all his spells cast)
Hidden Lore: Mages (A) IQ - Understanding the kinds of Mages, Colleges, the Orders/Covens/Guilds/Cults etc... You also know the Cost of Living, wages, and many things about the magical industry regarding HR. You also know that most powerful mages have cults/followers/devotees to draw magic power from (particularly because of how regular magic system works)
Information Analysis: Thaumatology (H) IQ - the ability to understand magical doctrine and practice, you are able to apply your Thaumatology in gathering information regarding strengths, weaknesses, opportunities and threats. Defaults to Thaumatology-6.
Expertise: Security (Optional Specialty: Thaumatological) (A) IQ - Very Specific regarding Magical information Gathering, Intrusion, and Counter-Intelligence. All the social engineering related practices with magic.
Strategy (Thaumatology) (H) IQ - waging a Thaumatological Campaign, defaults from Information Analysis: Thaumatology -4. Since magic has many elements of logistics and preparation, and how to organize magical elements.
Current Events (Thaumatology) (E) IQ - requires Hidden lore Mages, knowing whats happening currently. Basic Political situation and Atmosphere among the many magical factions. Typically people learn about current events from their contacts, so sometimes you don't need it but sometimes its better to be the one to get the information yourself instead of 2nd hand.