Start with people you know and network. Let your friends and family know what you're doing, what your goals are, and where you hope to be in 1 year, 2 years, 5 years...etc. Above all else, go fishing and don't pre-occupy yourself with making sponsorship your priority.
I made the mistake of putting too much effort into getting sponsors several years ago and it killed my fishing/performance. I was so preoccupied with sponsors I couldn't concentrate on fishing, and it showed. I also didn't like who I had become, as I thought being sponsored was the do all be all of bass fishing.
By economics, not choice, I took a 1 year step back from fishing tournaments, and darned near recreational fishing. What a difference the break made, as now I'm back to having fun, my concentration is back, and in my first full season back I have a top 20, 2 top 10's, and a top 5 and have worked from 118th in points to 14th, as I started the season a tournament behind.
My wife's accounting firm sponsors me now by paying my entry fees when needed, but as of right now, my winnings from the last tournament have me paid up through the next 3 tournaments.
Good luck to you, and enjoy fishing, the opportunities will come but you can't force them... take it from someone who has "been there, done that".