I saw the sample of tenancy agreement, at the signature part:
"in the presence of:-"

So we need a witness here, am I right? Who can be the witness? must be a lawyer?

I draft all my own tenancy and over the years added clauses to protect myself further. But as per other threads, I always say, drafting the best tenancy agreement is not much help (except for the high class property) as obviously if the tenant wants to cheat, there are 101 ways of doing so.