Securing Front Garden from

Hi HoLers,

I wanted some advice about possibly securing our front garden, e.g. a letterbox outside and the gate opened only by key or similar. 

In the past two days, I've had one 'neighbour' (who lives on our block), going through our recycling bin (his head was inside our bin) and one 'neighbour' walking her 2 pitbulls come in and pick our tulips etc to take with her as she carries on.  It feels invasive, especially as neither, upon my talking to them (coming from inside the house so they knew I lived here) felt the need to apologise or explain, and both I have seen repeatedly on our street.

What have people done to their front areas to make them less of a 'free-help-yourself' area?

Thanks!