Have a little sheet with bullet points of your talk so if you get truly lost you can get back on track. Better than that is asking a member of the audience, just be straightforward, "I just lost my track where were we?" Most people forgive a rough-around-the-edges speaker if there's a feeling of informality and participation.

Also practicing but quality practice is the key. Record yourself and watch it. Practice in several different places. Practice in front of a friend. Practice at a Toastmasters. Skim your speech during the little spare moments you have. And if you start to get down go search through some tech talks, there's a lot worse speakers than you out there so find one and boost that esteem haha.