Funny, i own people all the time with finger blast.
1) Snipe them; i can land 3-4 shots onto a person easy from across the map cuz my visual(red/green markers appear very good on my screen
*kisses video card*
2) Knock them down and put 4 straight finger shots up their arse. This usually kills them and if not then just time a back flip and swoop to finish them off with style
Also once you go form 2... ROFLMAO finger laser spam time.. You can shoot the laser like 10-20 times per go and charging up is faster when ur in form2. I kill so much people with Freeza form 2 using f.laser that i get accused of hacks lol.
When im Form 2, i either spam snipe with finger or knock some1 down and finger burst or just single shot(which i think is more powerful) they usually go down and fast.