aim for 的宾语是名词, aim to 后面接动词原形, aim at 后面可以接名词或者动名词。如:
The movie aims for comedy. 这部电影想要拍成喜剧。(《韦氏高阶英汉双解词典》p.46)
The movie aims at comedy [=the movie is intended to be a comedy], but it really isn't very funny. 这部电影本想拍成一部喜剧,但它实际上一点也不搞笑。(同上)
If you're trying to lose weight, you should give yourself a goal / target to aim for. 如果你想要减肥,你必须给自己设定一个目标。(同上)
They aim [= intend] to reform the government. 他们想要对政府进行改革。(同上)
We aim [= plan] to arrive there at around noon. 我们计划在中午前后到达那里。(同上)
The new system is aiming at reducing costs. [= the purpose of the new system is to reduce costs.] 新系统为的是降低成本。(同上)