my car doesnt start most of the time, its a renault clio 1998 R reg?

im having problems starting my car, sometimes it will start no problem, but most of the time it takes me many attempts to get it going, it is turning over when i turn the key. it can start first time, i go up thr road to the shop, and it wont start comming back. it is also cutting out sometimes whilst im driving it. it happens when im slowing down. it wnt start up again, and i have put hazzard lights on untill i can get it going. please help, i have got no clue bout cars.