You'd like to learn a language for work, school or travel?
1.) Study/practice daily. If it doesn't stay fresh in your mind there is a high chance that you could forget what you studied. Only studying a few minutes every other week isn't really going to get you far.
2.) Spend 15 to 20 minutes daily listening/watching something in your target language. Pause regularly and repeat out loud or silently in your head a sentence or two you just heard. Replay the video and see if you were right. If you were right, continue the video.
3.) If you're trying to learn vocabulary- Make note cards. Write the word on the front and definition on the back.
4.) Keep your goal in mind. Write it on a piece of paper and put it where you can see it daily. Determination will help you. If learning this language is very important you, you will make time for it.
I'm always surprised when people think studying for a few moments every two to three weeks is going to help make them 'fluent'. People make every excuse under the sun as to why they can't study.
A routine and consistent studying habit will help you become fluent.