Sucking a guy's cock and going all the way by swallowing his load I believe has to be motivated by desire and affection for your guy. With those feelings and emotions in mind, you can do anything!
Unfortunately we do live in the age of HIV/AIDS and other STD's, so caution is a plus.
In my case, I hadn't been to a JO group in years, really since the mid 1990's and hadn't had sex with a guy since the late 1990's. For me that is mutual masturbation and sucking his cock.
But in early December 2011, I did go to a local JO group and met there a hot, wellhung guy who has taken a liking to me and visa versa. We have become occasional bate buddies. Unfortunately he lives 300 miles from me so our contact is only occasional.
Well being an older guy, I masturbate now maybe once, sometimes twice a week. Well in the weeks following the circle jerk, I didn't masturbate because I was extremely busy. So one night a few days before Christmas, I found myself dreaming about my buddy. I dreamed that I was sucking him off! I awoke towards dawn with a delicious erection oozing precum! I came close to having a wet dream!
Brian did come up to see me. He was visiting a friend of his for a couple days following Christmas. Brian and I connected for a JO session the afternoon of December 26. He's a guy who really gets into bating and edging for hours in fact. Anyway he was edging for a good 45 minutes, riding the edge of ejaculatory inevitability. Then he presented his wellhung cock to me. I sucked him to the root and his HUGE cock fit my mouth and the back of my throat perfectly! I was careful to hide my teeth behind my lips as he fucked my face! I didn't gag once! He shot two volleys of cum into my mouth which I swallowed and then pulled out and shot the rest of his load all over my left thigh! He was apologetic. But we laughed! I certainly enjoyed his buttery, tangy cum! He certainly loved my suck action. He wants to do it again!
What I am saying is that sucking a bud's cock is an expression of affection and tenderness. You will not go wrong with that.