Buy a good vocal exercise book, follow what the book says and you will be able to improve in a short while. Good luck. Regards.

practice ... BUT don't strain - you need to find your range by doing scales - work this range up and down but don't ever strain! my range is 2 and a half octaves atm! i don't think it's going to go much more than that though lol bottom G top top C! good luck with the singing x

Do crescendos and decrescendos, try to close the gap and smoothen the transition between low, middle, and high, you don't necessarily need a vocal teacher if you are just trying to get the middle voice going, but it is a good thing to have one as long as tthey teach speech level singing... I had the same problem, but I like to do what they call 'belting' so I would start on a low note, and while using diaphragmic breathing slide up slowly to my highest not, and slide down again... where ever the gap was I would work on the most... if you are using mixed voice, then you start on a low now with your chest voice slide up and smoothly try to make it to a note that uses your middle voice, then try to work my way up to a voice that uses my head voice... if you know none of these terms just look it up, it helps understanding what happens when you sing different notes, either way work on you passaggios a lot, to get your higher voice stronger, it depends if you are doing falsetto in the first place or not, if you are its difficult to add much to it, if you are using you chest voice to hit high notes(belting) then work on breathing exercises so that you won't tense up, leaving you with bad technique... sing your own voice, just be yourself when u sing and much should be accomplished with the help of dilligence ... also record your own singing and you will truly c how you truly sing...

OMG i have this same problam, I would say practice I had voice lesson for a little bit and she got me to sing song that where in my rang and then a little bit out of my rang to practice getting better.