How to make raised beds

Im going to buy some decking boards - 2.4 metres in length, as the next size up is 3.6 which would not fit in my car.  Will also get some battens to cut down to about 30cm and make a point a the end of each for the corner posts - Wickes and B&Q don't seem to sell short ready made stakes, only long ones, so will have to make my own.

I want my beds to be about 3 metres long, so will have to but two lengths together, and use a wide piece of wood / stake to screw both pieces against.

I was then just going to screw it all together with wood screws and a drill - just drilling the screw straight in. Will this be OK, or do I need to drill the hole before hand?

I have made my raised beds from pallet timber and never used a screw yet. 

I like to call them my lazy beds. 

All I did was draw back the soil to make a small trench and then pop the boards in and refill with soil around and then around the outside hammered some stakes/pegs in to support to stop the soil pushing the sides out when it settles.

Works for me and they have not moved in a year