In general, it is better to prioritize a few powerful (fully upgraded) mods rather than several weaker mods; Quality is better than Quantity!
And always look at the stats of your weapon when you decide which mods to use; a mod that increase e.g. Slash damage with 50% is useless on a weapon that only deals Radiation damage - 50% of zero is, well... zero!
For warframes you should generally prioritize your mods in the early game as:
- Health, shield and energy mods: Flow, Redirection, Vitality.
- Any aura mod matching your warframes aura slot as this will give you additional mod capacity.
- Power mods: Continuity, Intensify, Streamline, Stretch.
- Shield regeneration: Fast Deflection
- Mobility mods: Rush
More experienced players will learn to prioritize according to their playstyle and the current Warframe. For instance, when playing Rhino you are likely to use his Ironskin ability as much as possible. This ability is boosted by the Health, Armour and Ability Strength, so you might consider modding these your first priority.
Do not waste mod slots on elemental resistance mods or bleedout mods.
Remember to take the following as a general guideline and ALWAYS look at the stats of your current weapon when deciding how to mod it!
For weapons you should generally prioritize your mods as:
- Damage mods: Hornet Strike, Point Blank, Pressure Point, Serration.
- Multishot mods: Barrel Diffusion, Hell's Chamber, Lethal Torrent, Split Chamber.
Your next priority depends on the stats of your current weapon:
- If your weapon has high Critical Chance and high Critical Damage, you can increase the damage of your critical hits with these mods: Blunderbuss, Pistol Gambit, Organ Shatter, Point Strike, Ravage, Target Cracker, True Steel, Vital Sense
- If your weapon has high Status chance (~25% or more) you should prioritize 60/60 dual stat Elemental + Status chance mods: Malignant Force, High Voltage, Thermite Rounds, Rime Rounds, Toxic Barrage, Shell Shock, Scattering Inferno, Frigid Blast, Pistol Pestilence, Jolt, Scorch, Frostbite, Virulent Scourge, Voltaic Strike, Volcanic Edge, Vicious Frost.
- If your weapon has both high Status and Critical Chance, you can make a dual Critical/Status builds - in this case also consider using the Hammer Shot mod.
- If you are only fighting low level enemies or your weapon only have low Status and Critical Chance, you should prioritize modding for primary Elemental damage mods (Cold, Electric, Heat and Toxin). Remember: Some damage types are more efficient against certain enemies, so consider this when choosing which elemental mods to use.
If you have any spare mod slots, consider using the following mods:
- Fire-rate / attack-speed mods: Fury, Gunslinger, Shotgun Spazz, Speed Trigger.
- Physical damage mods (Impact / Puncture / Slash) - mod your strongest physical damage only.
- Ammo conversion mods ***
Some weapons e.g. sniper rifles and shotguns have a small ammo capacity and you may run out of ammo against high level enemies (especially if you have equipped some fire-rate mods). In this case you may need to use an ammo mutation mod - however this will cost a mod slot that may be better used for boosting your damage. Instead consider using the Carrier or Carrier Prime sentinel to assist in restocking your ammo or if you are a member of a clan, you can also buy a blueprint for Ammo resupply kits.
In general, physical damage mods (Impact, Puncture and Slash) are weaker than the elemental damage mods. However, if your weapon already have a lot of e.g. Impact it should scale well if you mod for extra Impact. If you play Nekros you should pick some weapons with large amounts of Slash damage and mod for even more Slash, as this will cause your Desecrate ability to drop even more loot!
Status chance mods are not important in early game as most enemies are easy to kill, but when you are up against harder enemies with lots of shield and armor Status becomes more important as the Status effect procs can do massive amounts of damage-over-time (DoT) or reduce the shield/armor/health of the enemy making them easier/faster to kill.
Hint: Once you unlock the Simulacrum by earning syndicate rep with Cephalon Simaris, you can test different weapons and mod configurations against various enemies and see what works best for you.
Most of your mods you will get from just running missions over and over again and hoping for RNG to give you that specific mod you need.
However, each 14 day a NPC named Baro Ki'teer will arrive at a random relay station, where he has some special items for sale including a few Primed mods - these are extra powerful versions of your standard mods.
To buy a primed mod you first need to get enough credits and Dukat's. A Primed mod may cost e.g. 350.000 credits + 350 Dukat so a bit of farming is required...
How to get Dukat's to buy Primed Mods:
You get Dukat's by selling Prime blueprints or Prime components to the vendor machine a few meters to the right of Baro Ki'teer.
Prime blueprints are rewards from Void Fissure missions. To get the reward you must equip a Void Relic before the mission start and then kill enemies until you have collected 10 void fissures, which will then crack your Void Relic. You can farm Void Relics by running e.g. Defence or Excavation missions.
Important: DO NOT solo void fissure missions - always run those in a 4 man group. The reason is that if you are not satisfied with your own reward, you can also see what reward the other team members got from their void relic, and you can then freely choose one of the other rewards instead if you prefer!
Which Prime blueprint should I pick as reward?
If you are farming for a specific Warframe or weapon, you should of course select that blueprint if it drops.
If you are farming for Prime blueprints to sell for Dukat you should select the most expensive Blueprint - just look at the color of the reward text:
- Bronze blueprints sell for 15 Dukat.
- Silver blueprints (reward text actually looks more white than silver) sell for 45 Dukat.
- Gold blueprints sell for 100 Dukat.
When you are doing a Void Fissure mission you will collect some void fissures that can be used to upgrade a Void Relic to Radiant level - this improves your chance of getting a rare blueprint from the relic and thus also improves on your chance to get more Dukat's if you chose to sell the blueprint.