Aspirating is very easy and I am not sure what would worry you about this part. Once you hve the needle all the way in, lightly pull back on the plunger, if you are in a vein blood will go in the needle very easily, if the plunger doesn't move you are good to inject.
Injecting really isn't very hard. Get some 25g needles and you will not feel a thing. I was suprised with how painless it was my first time. Just stick it in slowly to help avoid nerves, but if you hit them, you are going slowly so you will know before you go through one, which I think is always a positive thing.