I think the other thing is making sure that executors / heirs know where the will is stored, and destroy old ones!
You also need to be aware, for instance 'to my grandchildren Topsy & Tim', or 'to my grandchildren'.
Most solicitors advise against leaving very specific sums of money or properties because it can cause problems as circumstances change.
My grandfather made a will when I was young, in which he left me £250 - which would, at the time, have been a 25% deposit on a very nice house in our village. He left his house to one of his sons, and £1000 to the other. When he died, 50 years later, his house was worth £250k! Fortunately the brother sorted it out amicably; and his love and support gave me a good start in life, so a nice memento was all I wanted.
I have made 4 wills in my life: a DIY when I was young; used a solicitor when I had children, to appoint 'testamentary guardians' and ensure money was available for them; another DIY when they grew up; and now another with a solicitor so we could arrange inheritances for GCs.