It`s always a bit difficult trying to explain such things....much easier to show you,but i do it as follows,and never miss a worm
Once you`ve found a nice cast and blow hole,take to spits of sand from in front of them,then a final spit from behind.The first spit is more of a "pilot hole" and should start around 8" in front,the 2nd spit should be taken from around 2" in front,giving you clearance for your final spit...the final spit is obviously very important,and should start around 2" behind the cast n blow hole,but you must make sure that your spade goes down straight,otherwise you`ll cut a lot of worms.The temp` dictates how deep the worms are,but even in summer,they can be pretty deep on some beaches,so make sure you get your spade well down....it`s that last part that many diggers fall down on...to my mind,there`s no point wasting previous effort by not giving a bit more on the final spit.
If you find that you`re cutting worms,then you`re either digging too close from in front or behind the cast,or not putting your final spade in straight.
You can pump blow lug,but it is much better in water....place the pump directly between the cast and blow hole and pump straight down...a gentler approach is required for blow,as opposed to black lug,as it`s much softer/fragile.
You can keep blow lug in good condition for a few days.Either wrap in newspaper (don`t overcrowd it) and keep in the fridge,or keep it in a bucket of fresh sea water...again keeping them cool is the vital part....add a cool block each day to the water.,and change the water (removing any dead/blown worms)daily.