DISCLAIMER: The views expressed by this author are his personal opinion and in no way should cause a debate. Wrong or right, it is how HE does it and will do so unless God strikes him down-- dead.
I only use transitions when absolutely needed to tell the story. I usually have a couple of (to cleverly convey a visual continuity from one scene another) MATCH CUT TO: but I never use a CUT TO:
I do however, always use a FADE IN: at the beginning (left justified) and a FADE OUT: at the end of the script (right justified).
This is so they know they got the whole script, from beginning to end.
As for credits... I wouldn't worry about it, unless you have a unique and interesting way of presenting end that would make a director (or producer) go-- "That's cool. I love it." But again, normally it's just not done. I don't.
Now. On to the subject of directing in a script. Yes it's like telling someone how to dress (that someone being a director). But a vast majority of spec scripts do not go to a director first, but rather a producer, agent, manager, contest, etc... A director is usually hired after the script is optioned or sold.
Now I am NOT saying to write your script with camera directions, so please don't anyone misread the next few sentences.
Screenplays, by nature, are supposed to be visual. Yes, write with a sense of the visual, but don't make it look like a technical manual or "film by the numbers" script. Don't use any shooting script elements (transitions, camera directions, etc) unless it's the best way-- or better yet, the only way to convey your intentions of telling your story...