Merit Overview
Specific stat merits give a 3% increase per rank and are great for high stats and get even better the higher the stat is. Strength merits are a slightly more valuable investment than the others as that stat has the least number of educations/perks that boost it.
Weapon mastery merits give a 3% increase to damage and accuracy for a specific weapon type and are great if you use a specific weapon (which you should consider, so you can also take advantage of the combat bachelor perk).
Nerve merits are a waste and you generally shouldn't invest any merits here. The value gained from them is far lower than the other combat/utility categories. If you want to increase your crime experience you should invest in Crime Success Rate merits instead.
Life Points and Critical Hit Rate merits are crucial combat perks and you should invest heavily into or max them if you war often. Both are very important in the new attacking system.
Education length merits are good if you rehab consistently before you get kicked from education. I invested 5 ranks here a long time ago and it paid off a lot over time, but if you only have a few education tracks left it's not worth it. It's more effective the longer you plan to grind out courses.
Crime success rate merits give a 3% success rate bonus to crimes but only matter if you care about crime experience, and are quite good early on when you're still ranking up your nerve bar. There is always a possible red/blue result rate per crime (some crimes have no reds), so investing heavily here does not necessarily prevent you from failing or cause you to always succeed.
Awareness merits are totally personal preference, I don't see much point in them myself.
Bank Interest merits are good if you're constantly rolling over a 2b deposit at the bank.
Looting merits for those sexy mugs, but are personal preference and pointless if you don't mug.
Stealth merits I personally find pointless but some people like to be ninjas. It has some value during faction wars where you can potentially avoid more retals due to having been stealthed in the attack more often.
Hospitalization merits I also find pretty pointless as long hosp times for enemies is a drawback during wars. It can be decent for harvesting nerd tears when they see a 6 hour hospital time.
General Information
If you can afford it, you should buy all the extra merits available to you at the points store, and another one every time you level up.
If you are a newer player, all the %-increase stat and weapon perks aren't going to be very good for you right then since your overall totals are low, giving you a much lower comparative bonus. You should consider focusing on education reduction, bank interest, and crime success rate (only if you're really interested in upgrading your nerve bar).
Keep in mind that it costs 55 merits to buy 10 ranks in a single category, but only 15 merits to buy 5 ranks. Spreading merits around can get you a lot more "very good" buffs as opposed to a few "awesome" buffs. To steal an example from the other merit discussion thread, 10/10 education gets you -20% education for 55 merits, which is great if you want to grind out education courses. Or you could take 5/10 education, 5/10 strength, 5/10 clubbed weapon mastery, and 4/10 defense, giving you -10% education, +15% strength, +15% club damage + accuracy, and +12% defense. Is losing 10% education time worth the extra strength, weapon mastery, and defense? It's up to you, but think about the tradeoffs you can potentially make with merits instead of trying to get 10/10 in just one or two categories, particularly if your overall merit total is low.
Specific stat merits give a 3% increase per rank and are great for high stats and get even better the higher the stat is. Strength merits are a slightly more valuable investment than the others as that stat has the least number of educations/perks that boost it.
Weapon mastery merits give a 3% increase to damage and accuracy for a specific weapon type and are great if you use a specific weapon (which you should consider, so you can also take advantage of the combat bachelor perk).
Nerve merits are a waste and you generally shouldn't invest any merits here. The value gained from them is far lower than the other combat/utility categories. If you want to increase your crime experience you should invest in Crime Success Rate merits instead.
Life Points and Critical Hit Rate merits are crucial combat perks and you should invest heavily into or max them if you war often. Both are very important in the new attacking system.
Education length merits are good if you rehab consistently before you get kicked from education. I invested 5 ranks here a long time ago and it paid off a lot over time, but if you only have a few education tracks left it's not worth it. It's more effective the longer you plan to grind out courses.
Crime success rate merits give a 3% success rate bonus to crimes but only matter if you care about crime experience, and are quite good early on when you're still ranking up your nerve bar. There is always a possible red/blue result rate per crime (some crimes have no reds), so investing heavily here does not necessarily prevent you from failing or cause you to always succeed.
Awareness merits are totally personal preference, I don't see much point in them myself.
Bank Interest merits are good if you're constantly rolling over a 2b deposit at the bank.
Looting merits for those sexy mugs, but are personal preference and pointless if you don't mug.
Stealth merits I personally find pointless but some people like to be ninjas. It has some value during faction wars where you can potentially avoid more retals due to having been stealthed in the attack more often.
Hospitalization merits I also find pretty pointless as long hosp times for enemies is a drawback during wars. It can be decent for harvesting nerd tears when they see a 6 hour hospital time.
General Information
If you can afford it, you should buy all the extra merits available to you at the points store, and another one every time you level up.
If you are a newer player, all the %-increase stat and weapon perks aren't going to be very good for you right then since your overall totals are low, giving you a much lower comparative bonus. You should consider focusing on education reduction, bank interest, and crime success rate (only if you're really interested in upgrading your nerve bar).
Keep in mind that it costs 55 merits to buy 10 ranks in a single category, but only 15 merits to buy 5 ranks. Spreading merits around can get you a lot more "very good" buffs as opposed to a few "awesome" buffs. To steal an example from the other merit discussion thread, 10/10 education gets you -20% education for 55 merits, which is great if you want to grind out education courses. Or you could take 5/10 education, 5/10 strength, 5/10 clubbed weapon mastery, and 4/10 defense, giving you -10% education, +15% strength, +15% club damage + accuracy, and +12% defense. Is losing 10% education time worth the extra strength, weapon mastery, and defense? It's up to you, but think about the tradeoffs you can potentially make with merits instead of trying to get 10/10 in just one or two categories, particularly if your overall merit total is low.