The best strategy for learning algebra is to keep up with the class. The moment the teacher begins to talk about something that you don't fully understand, raise your hand and ask a question. Have the tough parts explained to you. If you still don't understand, don't just let the rest of the class stampede past you and leave you choking on their dust. Try to stick with the rest of that class period, and afterwards stay and talk to the teacher. Have him or her explain it again right there on the spot to try and get a better grip on it.
Often if you look for an alternative source of teaching, you will find that things can be explained in a much better way than your textbook does.
The first option is to look at the tutoring that your school offers. Most of the time they will offer at least something for free. Drop-in tutoring is particularly helpful. Schools keep a few people on hand who are experts in a large amount of things, and usually math is one of them. If you have a concise math question that you can go in and enquire about, then by all means do so. Your instructor might explain things in a way that is not ideal for your mental processing style, and if that is the case then it would certainly be helpful to get the help of someone who can explain it in a different way. If you hear a phrase that you can identify with, the problem may click with your mind and become clear.
The internet is another extremely useful tool for anyone who wants to get some extra help with their algebra. A speedy search will lead you to professionally written tutorials on whatever you are having trouble with. Not just one tutorial, but literally hundreds. With that many options available in one place, you should have no problem finding at least one that explains it in a way that you get. If you still don't understand, you have two options. The first is to try to persevere through the rest of the semester, and the second is to drop the class and attempt to enroll in a class that moves at a slower pace and covers some of the earlier concepts.