When I was 9 years old I learnt Italian for 3 years and could speak it better than English (English is my first language).. After getting to high school and started learning French, I lost the Italian (or spoke mixed Italian and French) but eventually lost it completely because I had noone Italian to speak to.
I then learnt French for 3 years at high school, did it for my HSC (top 10% mark in the state) and then left school and did not speak French for 6 years. I chatted in French on msn with a couple of people but not much at all.. I went to France last year and picked it up again pretty easily..
I also learnt Greek over the last 4 years just listening at home and went to Greek school for 6 months…when I went to Greece last year I picked up about 90% more of the language by listening and using it every day than I did in 4 years at home.
I would recommend that if you’re going to learn a language, to ensure you have someone there to speak to constantly, or you will lose it. I learnt Italian the best of the 3 but since I didn’t have anyone to speak to I lost it. Can remember small parts now but not enough to get me by.
I guess the best advice would be to learn with someone else so you can practise together. It makes a huge difference.
Good luck!