Learning Another Language

I'm currently learning French but want to learn German and Russian later. How soon should one wait before moving on to a new language?

I suppose it depends on how eager you are to learn French vs Russian/German. If you start the Russian or German right now, you'll have less time to spend on French.

i think it's better to achieve low intermediate level at French and just after start to learn Russian or German. when you have basic knowledge in language you keep that better in mind not forgetting in comparison with that you start to learn some languages knowing all of them bad and that will take you more time to learn one of them any better because you won't be concentrated on just one language.

I would have to know more before I could advise you. If you are at least high-school age, I would say it is fine to start German if you have the resources/contacts to pursue the language. Russian is also a good choice if you have Russian immigrants with whom you can practice.

How good is your ear? How well do you memorize?

Unless you have some specific time frame then just start learning them both.