A Thinker's Guide to Acting...
If you're a potential over-thinker like myself, try and forget everything you know about other jobs. Forget about right and wrong, about being like someone else. Forget about thinking. It's more interesting to see what's different about us doing a part, not how we think it's "supposed" to be done. As in our characters sometimes being careless, sometimes taking risks, sometimes being unpredictable, because those things make us real. Often just being ourselves in the real world has negative consequences, so it's easy to get used to putting limits on ourselves to be like everyone else, but that same uniqueness is a must-have source of creativity for acting.

1. At First, Don't Bother Memorizing
   
   Pre-read by yourself, but don't force memorization.
   Forced memorization will restrict you. Instead, be free enough with your own thoughts and words so that you build from the inside out. You'll learn the script just by doing the steps below.
    
2. Start by Paraphrasing
   
   Quickly scan your lines, pick ONLY 3-5 key words, then look up and ad-lib using those key words.
   Later, gradually replace your ad-lib with the written lines to make them yours. You've got to FIRST have the freedom to find yourself in the character, in your own style and in your own words, before you can fully give to your partner, the script, or anyone else. Once you've found yourself, you'll automatically have the confidence and most of all willingness to really communicate. From there everything starts to come naturally. This is definitely not saying the script and direction isn't important-- they very much are, and you'll have to eventually memorize your lines and work well with the director and writer for most productions. But paraphrasing from your own words first will give you the real essence of the dialogue from your (not the "character's") point of view.
    
3. At First There is No Style But Yours at That Moment
   
   Initial "right" and "wrong" ways of delivering lines do not exist.
   If there was just a single way of doing things, then we wouldn't have yearly productions of Hamlet or any artistic work (IMO each production is a new interpretation). How you interpret your lines as an actor/character is what people want to see, so have the courage to just do it any way you want vs. another actor/person. Feel like laughing during a "sad" scene? Do it. Real people avoid sorrow by laughing all the time. Have a bad train ride earlier and a bit bummed? Use it. Who's to say the scripted character doesn't laugh off sorrow or didn't just have a bad day, too. Whatever you feel is real because you're the one doing the part at that moment. Best is you can do it different the next time if that's how you feel. The freedom to do this comes from the steps above. Yes, you can later adjust your performance based on director/writer feedback, and a significant part of acting is being able to take direction and discover new interpretations, but first start with your own reaction at just the moment it comes to you and you may very well find a certain way feels best.
    
4. Read Near Someone to be Inspired
   
   Make every conversation intimate.
   Acting is a collaborative endeavor, so don't let social anxiety or personal space issues overwhelm you (or, if they do, you might think about a different profession). As a professional actor, you'll often be asked to enter your partner's personal space for effect, for a better camera angle, etc, and that's just part of the biz and not really a violation if both agree (so agree on it first). Proximity also lets you share energy and play off each other, which is hard to do if you're reading in isolation. One way to start is to just share the same script, because it encourages you to collaborate and share the entire experience with your partner.
    
5. Mark & Read for Each Other
   
   Take turns marking your place in the script while reading together.
   If you're sharing a script as in above, try this: Reader, mark your own end line with your finger. Listener, listen (don't read) to your partner say the words, then look down and pick-up where your partner marked their end/your start. Remember your keywords/cues in the steps above or ad-lib at first so there's no pressure. Words and paper don't show expression, your partner does, so you have to be listening to them while they're reading in order to react to them. This is also why sharing a script is beneficial, because it builds energy between you two. Once you've done it enough, you naturally build a rhythm going back and forth.
    
6. Be a Voyeur
   
   Closely listen to your partner.
   Listen to them when they're talking and don't give them a reading (presuming you have a director because "direction" is their job, "connection" to the scene is yours). Try to read their eyes, movements, thoughts, and gestures as the real person sitting next to you. After all, the actor and character are the same. Are they happy, sad, even nervous about reading this scene, distracted by traffic on the street or the filming itself? If the real person you're reading with bores you, then you're bored, no matter what the words on the page say. If they interest you, then you're interested. Your natural reaction will automatically be just as much or as little (little is OK!) as there needs to be at that exact moment. Pretending something else, like that they're not nervous or distracted if they in fact are, could be, well, faking it. You may very well be given direction later and should follow it to your best ability, but you've GOT to react to the reality of THAT situation because that's what's taking place right there in front of you.
    
7. Find the Love
   
   A fun shortcut to a scene's core is to just find the love in your character.
   Sounds melodramatic, maybe, but almost all creatives, like films & music, revolve around it. Needing love, denying love, resenting love, guilt over love. NOT necessarily sexual, but more generally just emotional connections to your own character or another. Tough guys in particular not convinced? Listen to the lyrics of almost any music (hardcore or not). See Brando in Street Car. Vin Diesel in Pitch Black (end scene w/ Radha Mitchell). It's what connects us to our words, to our feelings, to our acting partners, and ultimately to our audience.

Anyway, FWIW & IMO. But I think there is no wrong as long as you're connecting. From here, there are lots of different things you can do and places you can go, but these might be good ways to start understanding each other (especially w/ new partners or scenes).

Have fun!