Welcome to the community, JanYanSan!! I wish you the best of luck on your runs!! :)
One good way to learn the "ins and outs of speedrunning" as you put it, is to look at runs and guides for the game(s) that you're wanting to speedrun (which, in your case, is "Pokemon Yellow"). You can check out the "Pokemon Yellow" leaderboard here: http://www.speedrun.com/pkmnyellow I also highly recommend watching the world record run for that game, since it uses some of the most updated strats, which can help you get through the game even faster. The current world record for Any% Glitchless (which is probably the category that's ran the most) is currently held by Gunnermaniac3, and you can watch their run here: And lastly, I highly recommend looking through the guides and forums of the game. The guides, well, guide you through the game, and help show you the best strats on how to save those precious seconds. (Here's the link to the guides: http://www.speedrun.com/pkmnyellow/guides), and you can look in the forums for other tips that other runners have posted, as well as ask questions that the other runners can help you with (here's the link to the forum: http://www.speedrun.com/pkmnyellow/forum).
Once again, I wish you the best of luck!! :)