Reading the book of James?
Self control comes through prayer, patience, trial and time. God will hone you across time - I have the scrape marks to prove it. However, you can help the process!
Say the problem is speaking when you should not, or speaking too soon and regretting it, etc. Stop speaking your mind! Keep your mouth shut until asked or at least for a twenty count from when you wanted to say something.
You are impulsive. Well, try not reacting to your feelings, emotions and impulses! Oh so hard, but again try a twenty count to see if you can change your initial impulses before you act.
Yes, all of the solution require you to deny yourself the pleasure of reacting to the situation, through delaying. During that delay, you maybe be able to stop or modify the reaction you will be sorry for. During the delay, God has a chance to intervene (if you really want Him to). Even a 10% improvement is still a start!
For areas of self control wherein the end result is sin, do not expect a great deal of help - God expects you to be in prayer over your sin life, to not yield to temptation, to not allow opportunities to turn into temptations, and to avoid situations where opportunities exist for you in your area of weakness. That does not mean He will not help, He can, but He expects you to fight your problems and you do have the Holy Spirit as an assist in that one. Yeah the concept of self-loathing was rather strong in my early years!
And yes, examples I gave are/were my problem areas I had to kick the habit of, hence why I used them .....