I like this question. Which guitar you select depends a great deal on what kind of music you are going to be learning/playing.
First choice: Steel stringed or Nylon stringed? If you are planning to study classical or Flamenco methods, then you need a classical guitar, which will have nylon strings. For almost anything else, such as folk style, fingerpicking, bluegrass, etc... you should most certainly get a steel stringed acoustic. Especially considering that you\'ve already been playing an electric, going to a steel stringed acoustic guitar would be an easy transition. They are also louder, and come in more shapes / styles / appearances. I assume that for 150, you won\'t be buying a 12 string.
Second choice: Assuming you are looking for a steel stringed guitar, what body style do you want? The "Dreadnought" type body is the most familiar since C.F. Martin made it famous, but I don\'t actually care for them myself. I prefer a so-called "concert" or "auditorium" style body (using Taylor\'s names) with the larger upper bouts. I even like the smaller "parlor" guitars and travel guitars which are more compact and easier to hold. A "Jumbo" type guitar body can produce an awesome amplitude and great low frequencies, but you\'re going to pay more for the additional wood and larger case. A cutaway is useful, and I don\'t see any good reason to do without it in a steel stringed guitar unless money is an issue.
The rest of the choices: It comes down to a multitude of tiny factors that you will soon be confronted with. MOST IMPORTANT: You cannot choose a guitar without playing it. Therefore you must start visiting as many guitar stores as possible, and picking up as many instruments as you can. Try to develop a specific chain of chords / arpeggios / licks and fingerpicking patterns that you will repeat on every guitar you pick up. It helps to repeat the same thing on each one, because you may forget to test a particular instrument in every possible way. Try to play it loudly AND softly. Strum it fingerpick it, slap it and slide it. Do everything with it that you can think of, and build those into your evaluation ritual.
Don\'t be deterred by annoying guitar store employees who think you "shouldn\'t touch the merchandise." You CANNOT buy an instrument without playing it. They should be
helping you to pick up every guitar in the store, not stopping you. If they stand in your way, then consider taking your business somewhere else. You may only be spending 150 pounds, but they don\'t know that. Don\'t tell them. Handle the instruments carefully, and treat them with respect, but not like holy relics.
You will KNOW when you find the guitar that\'s right for you. Don\'t assume that every copy of an identical make and model guitar will sound the same. They don\'t. If you decide on a particular model, try to pick up every one they have in stock. They do come out different, no matter how automated the manufacturing process may be. This is one of the ways in which acoustic guitars are very different from electrics. Almost every one sounds unique.
I can tell you what I like and don\'t like, but that won\'t help you very much. You need to go out and pick up guitars and decide what YOU like and don\'t like. Have fun. This kind of shopping is very enjoyable.
