This keeps out air bubbles, which can break the condom, and leaves a space at the end for the cum. Roll the condom down as far as it will go. For anal intercourse , use lots of lube. Lube is great for vaginal intercourse , too. Add more lube often.
Dry condoms break more easily.
Don't leave the condom in bed with you. Throw it away and wash up. If you have intercourse again, use a new condom. Never reuse a condom. Guys, practice putting on a condom in a comfortable place where you have plenty of time by yourself.