Don't be shy guys :). Everyone does mistake, if you do it just face it. Ask your friend to practice english with you everyday.

"You is what you think" so just think you're a native speaker and pretending as a pro haha

If you don't know some vocabulary, find it on your dictionary and note it, so you can take a look to that new vocabulary in the other time. Oh, listening to western music, watching western movies, watching english youtube channel also help your pronounciation better.

Just remember every pro starts from zero and they learn from their mistake. Keep spirit guys!

I think one just needs to practise more, even speaking to yourself. It's also easier to speak English with non-native speakers at first as you will be on the same level and will be both making mistakes, it's not good adding someone else's mistakes to your own of course so might be a good idea to jot them down and then discuss each other's mistakes. But the most important thing is you will actually be speaking :)

Also, as English has regional variations plus it's an international language, native English speakers are quite used to all sorts of English I think, so it's very different from Russian in this sense, so I wouldn't be too shy speaking with the natives either.

I also forget words all the time, so I just rephrase whatever I want to say, you can get the same message across in many ways, even with gestures sometimes. Good luck!      

Do you know the distinction between long-term memory and the short-term memory?

Forgetting some words in the speaking or listening mostly consists in you do not put these words into your long term memory nor well practiced well by your mouth. 

I feel the same and thats why  i set up an account here. We are here to change it :)

When i forgot about some words i am trying to use my body language  or  use another words to keep the meaning what i want to say and then it stressed my a lot that somebody could not understand me.