Assuming you mean an electric powered drill, it may have the guts. A 1/4 inch hole is no problem, but a 1/2 inch hole will take more work. Clear the chips from the hole as you drill. I think the biggest issue with a hand held drill is if you will keep the drill neatly vertical. This will impact the quality of the holes you drill, if you do not.
A problem with a hand drill for metal is getting the hole in exactly the right place. A good solution is to use a center punch. This puts a small dimple, centered at the location you want to drill. The drill bit will now get started more easily without skating around the surface.
Keep your bits sharp. This will be important. A lubricant is also important, both for drilling and for the thread tapping process. For aluminum, you can use WD40 or 3 in one oil for this purpose, or a kerosene based lubricant that contains some oil. You will be surprised how much better a drill bit cuts with some lubricant, as well as in cutting threads.
Make sure that the piece to be drilled is held tightly in place. Clamp it down, or use a vise of some sort.