Practise speaking with someone every day.There is no better way.You can't learn to drive a car by reading a book,neither can you learn to speak by reading only.

Pretty much what Ruhti above said!

The "only" way, especially for shortterm, is frequent speaking practice. You should try to do 45-60 min slots and only talk in your target language if possible. Grab a pen & paper and take physical notes as you go, and review them the next day.

You need to do this everyday (or every other day), and after just 5 or 6 days you will notice a huge improvement, and begin to really look forward to sesisons and monitoring progress! 

Perhaps consider the iTalki June Language Challenge? I am doing this and aim to have 12*1hour Chinese lessons this month... hard work, but good fun. Let's see how it pays off!

I'd say being exposed to the environment. Although that does sound a little like exposing your self to radiation but it's the same idea. I usually encourage people to use media such as movies or TV series for english oral skills. NO SUBTITLE!!! but yes it is very daunting at first so i'd recommend either watching those titles you love so much you could recite the lines in your own native language and try re-watching it without the sub title. beyond that, BBC podcasts or news replays and skype conversation and a proactive attitude to getting yourself exposed to English environment is the best way to learn.

Practice is the best way.

You can try reading a book and then recording yourself to play back.

Yes, thanks for your great suggestions!