I have used the platform Duolingo and I think it is quiet good.
You can learn at your own pace, it is free and it is varied and quiet nice. And a good thing is that you can choose your mother tongue or the language that you want for the site.
You can also be in contact with other users to keep motivated. The platform has different tactics to make it easy and not boring, and there is also a forum where you can ask if you have any questions and find other possibilities to learn, or propose creating a group to practice the language by Skype, for example.
Here you have the link in English: https://en.duolingo