You just need to stick with it now... Your written English is already very good, so it's time you start tackling spoken English (since you "admitted" earlier that you have neglected it... ) When I get better at Russian, perhaps we could chat on Skype..
Anyway, one way to practice is to select an interesting text and then listen to it being read by a native speaker. Then you just read it back in the exact same way, or as close as you can...
The other thing for you to decide is whether you want to speak with a British or American accent. They are quite different as you know, so it's an important decision. You should settle for one or the other. Within British English there are lots of different accents. One good way of learning about the UK and getting a good British accent is to listen to BBC Radio 4 which is available on the BBC website.
Here is an example of a conversation (interview) between an English and an American woman. Both are clearly very well educated and this (plus their backgrounds) affects their accents. They are talking about the book "Georgiana, Duchess of Devonshire" which is based on a real story and was recently turned into a film with Keira Knightley. I haven't seen this film but I have heard it's one of the best British films of lately.
[video:3gwd1sdr]http://www.youtube.com/watch?v=woQ12Z7Jv_Q[/video:3gwd1sdr]
[video:3gwd1sdr]http://www.youtube.com/watch?v=0x9Zzfy5rQY[/video:3gwd1sdr]