How to improve lm386 amplifier circuit?

I am new to the world of audio amplifiers however i am  trying to learn. 

I have built a simple circuit using a circuit based on what I read in the database. The circuit works however there is a lot of noise and the sound quality quickly decreases at higher volumes however that may just be the speaker I am using. I am sure I need additional filtering capacitors however after looking at several example circuits I am confused about what where these capacitors should be and what values they should have. Please help me find a way to improve the audio quality to a decent level. Additionally I need to remove radio signals that are interfering with the playing sound. I am running the lm386 on 6 volts.

What value speaker would be ideal for this use? What capacitors do I want between my power rails? What capacitors do I want between my inputs? 

Here is my current circuit:

circuit