Modding isn't as easy as saying "Today I feel like starting a mod, how can i do it?" You need to have basic knowledge in at least everything for making a mod, coding is optional, because its... well hard im still struggling and im in uni with a class of it lol.
You need to have a good, hard working, respectful team that will do the work on time and to the best of their ability. VERY hard to find now a days because all people want to do on the internet now is ruin things and screw around. You should see if any of your friends are willing to help, and search around http://www.halflifexpert.com/ forums and ask if anyone is interested. Before you do this you should create a list of things that will be included in your mod, and the basic story behind it or people wont give it a second glance.