To be completely inept at building sandcastles and beg for your help?

[TheArtistFormerlyKnownAs]

This is our first family beach trip that my DCs are old enough to actually build sandcastles, and they are very excited to watch me build them. I have lovely and quite possibly imaginary childhood memories of building fantastic creations with all kinds of levels, bridges, tunnels, moats, etc., but unfortunately, my efforts so far are not remotely living up to my memories. My castles are pathetic small lumps that don't even stick together. Even my 3-year-old is unimpressed. I'm no architect but is this really that hard?? I would be eternally grateful for any sandcastle-building tips. Any suggestions for how to improve? Or what "tools" to use, beyond a few plastic buckets and spades from poundland?

My dh is great at sandcastles - he gets bored just sitting on a beach. First you make a huge pile of sand - which gets wetter as you dig further down. Pat this down as hard as you can. You can then form ledges which you can build small castles on using buckets. You can dig a moat out around and if you're careful make bridges. The most important bit is getting the sand packed down firmly enough.
Failing that get them to play at resaurants - my dd (now 14!) spent every holiday for years making seaweed soup, pies etc on the beach and serving them to us as we sat reading. Kept her well entertained! (and you just have to make "yum yum" noises occasionally..)

It's to do with particle size and being damp enough. Am officially a geek.

If fhe sand you are using is too coarse, it will never hold. Too fine, you're making mud pies.

You need to level out a good flat firm damp bit of beach before you start.
Use damp sand, a couple of different sized buckets are handy too.

Look at a plan of a real castle, Harlech is good one to begin with, base your castle on its design. As you get better you can get more complicated, I used to like Caerphilly with its double moat.

Get some flags, the children can collect stones & shells for decoration, carry water for the moat.