It depends on the traits you're trying to breed out, how well the afflicted can integrate (both in terms of their natural behavior and their appearance), and how cold-blooded you're willing to be.
Jews jew because they have too many alleles for mental illnesses and personality disorders, and because their intelligence is out of whack. High verbal IQ means they're good at persuasion. Retard-level visual/spatial IQ means that they can't easily empathize with others and they suck at anything requiring mental visualization and manipulation of 3D objects forward and backwards in time (ie, cause and effect). When combined with their high verbal IQ this means they're very good at persuading THEMSELVES to believe anything, but they're just smart enough to be anxious about it (which actually makes them more effective, similar to how predatory animals are anxious after making a kill). Other than that jew mathematical IQ isn't anything to write home about, but they aren't too dumb.
Asians are better than jews but not by a lot. Very high mathematical IQ and superhuman memorization abilities, probably due to social/sexual selection pressures in their societies. When your language has over 60,000 characters and you must be a scholar, a conformist, and be able to paint your alphabet you select for people who are good at memorization, social conformity in the face of disaster, and hand-eye coordination. Their visual/spatial intelligence isn't that bad (and there are plenty of outliers that are as good as or better than the average European), but it's not anywhere near as good as Europeans.
Europeans are very balanced between these three forms of intelligence.
Africans are mathematically retarded. They have between 12% and 20% more testosterone than Europeans - which explains why they are still functional in terms of hand-eye coordination and applied artistic ability - but their ability to visualize or understand the concept of consequences if awful. Verbal intelligence is hit or miss, but it's usually very low.
Australoids aren't human and they don't belong in this discussion. Kill the men, force the women to breed half-European girls, and do it again until the girls can pass as European - it won't take as long though since their traits are strongly recessive.
Asians probably require 75% European admixture to allow them to freely exist in European societies. This applies to Indios too, as they are just weird Asians. The dumber Asians and Mestizos will be taken care of by the complete lack of social services for mestizos and physical removal of the more violent, criminal, and subversive specimens.
Africans and jews must be at least 87.5% European admixture, but for different reasons.
Africans because they don't look human until they are almost 90% European. They will suffer anxiety from this and will probably chimp out of their IQ isn't very high. Plus their IQs are so low that it will take 3 generations of White men impregnating their women to reach this point.
Jews above 87.5% ethnic European admixture retain most of their rabbit-like sex drive and tendency to be perverts, but they lose a lot of the ethnocentrism (or the ethnocentrism is redirected towards their majority European ancestry). They don't have much anxiety, and they generally look only slightly spooky.
tl;dr
1. Kill or sterilize all the men.
2. Impregnate all the women with girls (and use high quality sperm donors with blond/red hair, blue/gray eyes, and a very high IQ).
3. Repeat when the girls turn 18 until you reach the correct admmixture.