Do you have natural rhythm?
Often part of the reason people can't dance is a lack of 'smoothness' in the way the body moves. This usually comes naturally or not but you can practice. It's all about relaxing the muscles that are usually quite 'stiff' like hips, knees, ankles, shoulders. I can't really explain it but you need to try and move these muscles as though they're made of liquid. Sorry, not helpful!
I'd also say start off small. Give yourself one or two moves to perfect over a couple of weeks. Practise on your own every day in front of the mirror. In a fortnight, add a couple more moves, then a couple more etc.
There are some ace instructional videos on Youtube
Have you looked to see if there are any dance classes near you?
I go to a Soca class where the teacher, who's actually one of my best friends, gives us a 'move' to perfect over the week. The following week at at the class we have to show her (as a group) how good we are. It's fabulous. Of course some people don't practise and she doesn't humiliate people who don't practise but it's good to just focus on one move and get that right.
Are there dance classes near you?