The importance of practice
When learning a language it is important that you use every opportunity you can find or create to practise listening to, speaking, reading and writing the language.
If the language you’re learning isn’t spoken in your area and you’ll probably have few opportunities to practise speaking it with others, though you could talk to yourself, and/or find language exchange partners online. One other useful way to practise using your language is to write it, which I find not only helps to improve my writing abilities, but also improves my reading and speaking as I tend to read aloud what I’ve written. It helps if you have a purpose for writing the language, such as corresponding with penpals, writing a diary or blog, gathering information, and so on.
If you haven’t written the language much before you’ll probably find it quite difficult at first and have to look up many words and check a lot of the grammar. So it’s best to start using short, simple sentences. As your writing ability improves those sentences will probably get longer and more complex.
In some ways I think learning a language as you’re using it is quite an effective way to study. You can learn new vocabulary and grammar as you need it, and by using it in context in sentences you’ve composed, you’re more likely to remember it. If you can get feedback and corrections from native or fluent speakers, even better.