Some thoughts from Peter Mead.  Here they are, using a mixture of his words and mine.

1. Don’t be intimidated by higher-tech churches.  If all you have is a smart phone, go with it.
2. Use eye contact differently.  Don’t look around, as you would if the congregation was arrayed before you.  Your congregation is ‘in’ the camera, so look straight at it.  If you are using a smartphone or tablet, use the rear camera (better resolution, plus your gaze will not be distracted by looking at your own face).
3. You may have ‘visitors’, but don’t get carried away.  You are preaching, first of all, to your own congregation.  Don’t be so vain as to think that countless thousands will be tuning in to hang on your every word.  Nevertheless, bear in mind the possibility of guests, and adapt somewhat to their probable needs.
4. Do work to make your illustrations and applications suitable for your own church setting.  But also bear in mind that they will be ‘out there’, and could potentially be misunderstood or misapplied by others.  So be careful, especially when referring to named individuals.  (In my own church, we pray for our own members only by first name, for this reason).
5. It’s tiring!  You’re preaching in an unusual situation, with an empty room and zero feedback while preaching.  (Even the feedback you receive after the service will differ from what you are used to – it may be more complimentary, but it may also be more challenging!).
6. Get good feedback, and use it.  Invite feedback from trusted friends on issues that are specific to online preaching.  ‘Did I touch my face too often?’  ‘How was my eye contact?’
7. Pray about everything.  We are used (I hope!) to praying about our content.  But will we pray, and ask others to pray, about our delivery?  God cares about the ‘how’ as well as the ‘what’ of preaching.  So should we.