RLM 02 Graugrün - Humbrol 78, 'cockpit green' - a bit too light and too green for my tastes but a good basis. Just add grey...
RLM 04 Gelb - Humbrol 154 (yellow)
RLM 63 - Humbrol 31, just about spot on
RLM 65 - Humbrol 65
RLM 66 - Humbrol 67 - this is a perfect match, not as dark as White Ensign's RLM 66.
RLM 70 - Humbrol 91
RLM 71 - Humbrol 117
RLM 74 - Humbrol 32
RLM 75 - Humbrol 27
RLM 76 - 40% Humbrol 65 and 50% Humbrol 28 and 10% white. Most brands of 76 have far too much 'blue' in them. Under certain lighting conditions RLM 76 was very bland..
RLM 78 - Humbrol 89
RLM 79 - Humbrol 118 - much better than the equivalent WEM RLM 79
RLM 80 - Humbrol 116
RLM 81 - Humbrol 155 based on XtraColor shade
RLM 82 - Humbrol 116 based on XtraColor shade
RLM 83 - Humbrol 86 based on XtraColor shade
A number of modellers have pointed out the lack of any reasonable equivalent for 72 and 73, the maritime greens. I looked at the Humbrol numbers for these shades a while ago and basically there is nothing that really comes close in the Humbrol range. A green/grey combination of 'similar' shades does exist though - 145 could be tried alongside 149, 91 with 32, or 66 and 67, although this latter combination might be too dark. To see the actual shades type 'Humbrol' and the number into google. In case you are wondering, yes, I do use White Ensign's Luftwaffe enamels, but generally find them too dark and too thick, requiring quite a bit of thinning. My last tin of WEM's RLM 02 congealed in the tin after only 4 or 5 uses so I was rather disappointed with that experience. The only Humbrol colour I'm not really happy with is the "02 Grau" equivalent - although Airfix/Humbrol are bringing out a new 02 Grau soon!