SSF4 has a different from the older games, such as SF2, it’s just something that you’re going to have to get used to. It’s considered quite slow in comparison to the alpha games, 3s, or ST, but can be quite fun once you really get into the meat of SF4 competition. Play it as if you’re brand new to fighting games and you’re trying to pick up the basics, which means going back to the fundamentals of fighting games. Learn your character through and through, their best pokes, the various uses of their special moves, what actions are safe and unsafe. Learn how to properly counter jump ins, whether it’s with normal moves, or special moves. The most important thing that you should be trying is learning how to control space. Learn how to dominate whatever ranges your character is good it, learn how to stay in that range, punish the opposing character for getting in that range, and how to minimize damage that you take from the other character. Blocking is a heavily underrated skill to learn, so learn it well.
Other than general tips, be sure to read all the stickied posts at the top of the forum for the ‘newbie’ section for more tips on intermediate/advanced play. Check out the stickied posts in SF4, as well as for your specific character to get some more tips. Other than that, you’ll need to ask specific questions if you want more specific answers.