I have done a bunch of conference talks and brown bag sessions this year (~45 in the past 2 years) and here is how I prepare for those talks. Sorry that the reply is a little long but I wanted to make sure you had a process to get started with. Remember that this is my process and you have to find what works best for you. There is no set time for how long each phase takes.
One of the first things that you learn when giving presentations is that fonts and font size matters just as much as the content. Below is a listing of the various font settings that I have found to be effective and how to set them in the programs that I use. If you have other programs that you use, feel free to leave a comment on the font settings that you use.
If you are planning on going to any professional networking events, user groups, or speaking at events, you should have business cards with you. Many times people think, I only need to have business cards if I am looking for a job. This is far from the truth. You should have business cards so that you can connect with the people that you have met. People tend to meet lots of people at events and without a business card, it is difficult for people to remember who you are.