Making a weekly schedule to devote certain times to studying will help begin study habits and improve grades. Study for 20-50 minutes, since your brain needs time to process info. You should find a comfortable place to study. If you prefer quiet or loud, adjust your place as necessary. Brain food is alright too, so having a small snack while studying is a good idea.
Make sure to get a good night's sleep. 7-9 hours is fine. A good sleep will help double your study time and help with studying in general. If you ever have trouble with words, check the glossary or dictionary for vocabulary and definitions. It's a good idea to study the most important things first, not just to read the entire passage. Highlighting and underlining is a good study skills and will make studying much easier.