The first thing to do is to practise your presenting skills in front of a mirror. Write yourself a script and present it. When you feel confident doing this try interviewing a friend in front of a mirror.
In school you will have a lot of opportunities to present something to your class, use this opportunity to gain experience of performing in front of your peers who can be the hardest audience to perform to.
Many charities and organisations are looking for volunteers to go around and give presentations about the organisation to members of the public whether this be a stall at an event or a planned presentation in a school. Try and get a volunteer position doing work like this.
Join a local or school theatre group, this will gain you experience in working in front of a live audience and scripted work.
Join a local hospital or university radio station. This again will gain you great experience in entertaining an audience and will give you the chance to work on your vocal skills. Being a TV presenter you have to present a good image and a good voice.
Create your own image, image is very important as a TV presenter so find an image that you think will either stand out or give you the best opportunity to get a presenting role.
Watch TV presenters from various shows and study them. Look at what works for them and how they handle situations and then bring the bits you like in to your presenting.
Buy a video camera or try and borrow one from someone you know. Film yourself doing some presenting then watch the footage back with others and look at where you can improve.
When you are happy with what you are seeing on camera, edit together a demo tape. To do this you will need a computer with editing software.
Once you are happy with your demo start sending copies to TV companies. Remember to find names of people at companies you need to send your demo to so you are addressing the demo to a member of staff, this can improve your chances of someone watching it.
Upload your demo on to the internet on sites like www.youtube.com and then direct people to the video. The more people you can get to watch it the higher up the videos ranking will go up so more people will see it.
By using a community website like youtube you can start your own internet TV programme on a very small budget.
Always be on the look out for auditions or opportunities to get on TV. This means checking TV stations websites and keeping your eyes on media related press.