i am looking forward to travel to south africa for 3,5 months soon, what do you think is the best way to prepare my english skills? I dont have alot problems with understanding and writing i think, but saying the things you want to say is something different. Thank you

Speak to native english speakers constantly.

that's what i am going to do there. but i'd really like to prepare myself a bit more, i didnt't really speak english for about 3 years

any other suggestions?

I've known a french canadian that learned english Purely from playing diablo 2... No Joke... I would recommend that you get yourself a mic and join a Teamspeak channel... Just sit there and talk with people.... Great way to improve your pronunciations and flow.

there is a website that hooks you up with people who will practice with you. I can't remember it ATM. but it uses skype to do it

watch english movies (with english undertitels) if you must.

English movies
Play online games where you chat with other english ppl
Read "The times" or other english lectures

yes, video game chat is a good one

I hope you dont wanna be sarcastic

I also can happen that you use slanv afterwards, which is not that wanted^^.
Something like "u" for "you".

But seriously: Playing Counterstrike global Offensive with native speakers was the best way to learn english.