hmmm...you should really try to sign up for a prep class. A few pointers...
1. Do alot of practice tests...under time pressure. Time is the biggest enemy.
2. Games...don't try to do them in your head. Solve them by shorthanding the clues and using graphs and other pictures and filling them out by using logical implications from the clues given.
3. Logical Reasoning...be anal. Every word counts. Every word. Read them fast and carefully. Practice reading them fast and carefully and get familiar with the type of questions they ask so when you begin reading the propositions, you are making connections in your head and anticipating what they are going to ask. Time is a huge enemy here. If you had all the time in the world, you could answer every question correctly. But time pressure makes you break down and not read things carefully. You must concentrate hard on every question and keep pushing fast. Your head should hurt.
4. Reading Comprehension...again, speed is key. Read, read, read in your spare time. Hard stuff. Get things from scientific journals where the writing is poor and very technical. Seriously. The writing samples they use are not very well written and they are trying to prove a point. Read alot of poorly written, technical and difficult stuff as practice. And do them fast. And read them VERY CAREFULLY. Each sentence counts.