Straight pool is easy if you know a couple of basics about it:
-avoid too much position play. Try to play mostly stun shots and clear the balls in groups
-always have an easy "spare" ball in case you play bad position or you're trying to break a cluster
-clusters can be broken with soft speed
-avoid using too much power on break shots, try to leave a good angle on the break ball instead
-choose the break ball early and think your way "backwards" to your current position, "before the break ball I should pocket this ball and before that..."
-learn to spot combinations and caroms from clusters
-after the break shot, try to clear the balls near the corner pockets to make more paths for other balls
-avoid kissing into and moving other balls with the cueball, you'll probably create a(nother) cluster
-learn how to make a good safety out of the 14-ball-rack in case you miss the rack on your break shot
-always remember, that if straight pool is easy for you, it's easy to your opponent as well! You will pay if you miss easy balls, trust me, I know !

-if you run more that 40 balls, you're definitely above average !
I don't know why, but during my years in practising straight pool, many people have had the mental barrier of having a highest break of more than 40. After you start practising you'll reach the 40 mark quite easily but getting over it is surprisingly difficult. If you can run over 50, IMHO it's only a matter of time when you run 80-100 or even 150. I took me some months to run 28, then a couple of months to run 39 and then 1-2 years to run 56. And that was 10 years ago... But don't worry about your high run, it's the average run that counts !