Slobber the joint and dry it, it makes the paper tighter around the weed and makes for a more even burn.
Or keep wetting the end of the side thats burning faster with some spit and ur finger. And hold that side facing down (i think down) Otherwise, roll a tighter joint and maybe grind your weed better.
The reason it's happening is because there is too much air on one side and it's burning hotter. Here's a technique if you can't roll a tight joint: After you roll the joint twist one side shut. Pinch the other side of the joint and shake it back and forth so that all the weed condenses towards the twisted side. Roll between fingers to loosen compacted bud, but keep it even. Cut off any excess paper at mouth piece. What I do is only seal half the joint, twist the end, shake it in, then I seal the other half so that it tapers down and no bud can spill out.
I pat mines down and if there's a filter in i shake the weed down to the filter and twist the end even tighter to pack it down then run it through my fingers to loosen the tight bud. I get an even burn 95% of the time the other 5% comes from shitty weed.