I'm good at basketball as well as soccer. ('as well' is used to add on to your own thought in the same sentence)
I'm good at basketball too. ('too' is used to add on to someone else's thought; ie. if they said, "I'm good at basketball," then you would reply with "Me too." [you can replace the too in the sentence with also, but you can't say "Me also." It sounds awkward])
Also is usually used when you finished your thought, but you forgot to add something, so you'll say "Also, ____." ie. To make scrambled eggs, you need to crack open an egg and mix it in a bowl. Also, don't forget to cook the egg in a pan.
Not sure if this makes sense, but hope it helps a little.