Use lube, and release the vacuum frequently. For every minute of suction, give your cock a minute of massaging. If done correctly, your cock will swell to enormous girth and when you cum, it will be massive.
You need a beginner sized pump tube. Over the years, I have outgrown many tube sizes. I am now fitting into a 2.5x7 inch tube tightly filling it up completely. My next tube is 2.75x8 inches, and it allows for more growth. As it is now, I can use the bigger tube for only a few minutes before forming the donut below the head. Still, it gets me hard and thick quickly and ready to go. I have never had any complaints about being too thick.