Jokes of an explicit sexual nature.

However some humour is good and will be included in your speech, including some risqué material if you wish. Remember that there will  probably be children present.

Alcohol, and the effect on speech making.

Presentation and preparation.

Length of speech and content. 

Other speakers. 

Coping with nerves.

Thanks and etiquette. The wedding is the best chance to combine and unify the relationship between in laws. It is also the easiest opportunity to cause bad feeling. REMEMBER this is a celebration!