For Al, I would start with the old standby 2 flute, ZrN coating. For non Al alloy use AlTiN coating.
For Al alloy, look for 45 degree helix angle or variable helix angle. These help with machining metals.
If you really get into Al Alloy, I would serious look at Onsrud single flute Al Alloy end mills… but definitely not until you’ve got some experience. For when you want to push things to edge and go for fancy finish quality.
Square end, ball end. Save corner radius (“bull nose”) for later.
0.125", 0.250" for sure.
Order only from known, quality sources.
Buy end mills in duals or quads, especially the smaller ones… It’s easy to break them.
I’m not much of an engraver. @WillAdams points to some good stuff.
mark
P.S.
Al alloy (e.g. 6061) can be machined dry. Lubricant - and how to use it - is a good idea. We can discuss them.