Get organized. Clutter whether it's in your room or on your notes spells disaster. Tidy your study area and organize your notes.
Make connections with what you are learning. Picture something in your mind when you are trying to remember a fact.
Use mnemonics. Take the first letter of a list of things you are trying to learn and make a phrase that's easy for you to remember. For example, to remember the colors of a rainbow, 'Roy G. Biv'. (red, orange, yellow, green, blue, indigo, violet)
Create a rhyme or set facts to music.
Get plenty of rest.
difficulties with taking notes
Use the recorder on your phone
Get copies of notes from your teacher or another student.
Bring a laptop or type your notes on your phone.
Keep your notes short. Your notes don't need to be complete sentences. You are the only one that needs to understand them.
difficulties with remembering what you read
If possible, get an audio recording
whisper read or 'read in an undertone'. This can even be done in a classroom and most students won't even notice what you're doing. If you can even slightly hear what you are reading, it will help you remember.
follow along with your finger.
re-read points you don't understand.
highlight and take notes.
difficulties with math
take good notes
ask questions
watch videos such as the Kahn academy
get a tutor
break multiple step problems down into smaller steps. For example, if you have 10 math problems with 5 steps, learn the first step and do that with all 10 math problems. Next, learn the second step and do that with all 10 math problems, on so on. (That way you are learning one step at a time, and repeating it several times before you move on).