Here I will list down a few tips which might help you to curb these problems,
Reading plays a pivotal role in speaking English. When you read, you know how to frame sentences, you know where to use which word. The more you read, the more you become fluent in that language. It is also very essential to read loudly so that you can hear how you are pronouncing the word. Is it sounding right? Or should I pronounce it differently? Everyday reading three to four paragraphs a day can be very helpful.
"Today a reader, tomorrow a leader.” – Margaret Fuller.
Now if you are a beginner how will you even understand that what you are reading is correct or not, for that you need to listen to people speaking English. The problem arises when you hear English in different dialects and then you finally don't know how to pronounce it. So choose the dialect. It's always better to choose the dialect of the place where you are living. For eg. If you stay in New York, it's obvious that you will speak in an American accent. If you are from India, Indians have an accent of their own. Always choose to listen to your own dialect when you are in the beginner's phase. Watch the English news channel of your own country. Find how to pronounce words in youtube mentioning the dialect. This way you will know exactly how to pronounce words. Now when you read loudly, you'll be able to distinguish how those words sound on television and how you are pronouncing it.
"Listening is a magnetic and strange thing, a creative force. The friends who listen to us are the ones we move toward. When we are listened to, it creates us, makes us unfold and expand." --Karl A. Menninger
Speaking plays the most pivotal part in Spoken English. It does not always necessarily mean that you have to talk to a person, or go on stage and address an audience. It can be in your own room, in front of the mirror. Use gestures while speaking. Get engrossed in the beauty of the language. Get so involved that it overpowers your nervousness. If you see yourself speaking in front of the mirror every day, you will gain confidence.
"It usually takes me more than three weeks to prepare a good impromptu speech.”– Mark Twain
We are never to old to pick up a book and start learning again. Grammar is a very intricate subject. To master it, you need a great deal of practice. You can always practice exercises from the internet or buy a standard English Grammar book, read through the rules and then solve the exercises. Make sure, there are solutions to those exercises so that you get to know what mistakes you have made.
"Only through practice and more practice, until you can do something without conscious effort."- Joe Hyam.
5. LEARN ONE NEW WORD every day
To improve your vocabulary the best way is to learn a new word every day. Buy a dictionary or download an app that will suggest you a new word every day. Learn its meaning and make a sentence with it. Try to apply that word in your everyday conversations. This way the word will stay with you. While reading if you come across a new word, instantly search for its meaning. These are a few excellent ways of enriching your vocabulary.
"Your understanding of what you read and hear is, to a very large degree, determined by your vocabulary, so improve your vocabulary daily." - Zig Ziglar
Speaking English might seem tough in the beginning but with a little practice and patience, the experience and the knowledge is extremely fulfilling.