List some. I practice the obvious ones on this list: http://www.expertboxing.com/punch-combinations/johnnys-punching-combinations-list 1-1 1-1-2 1-2 1-2-1 1-2-1-2 1-2-3-2 1-6-3-2 What are some more?
During my first year all I really practiced was the 1-2 (one or two in a row), 1-1-2 and 1-2-3. I think one shouldn't worry about combinations too much at the beginner level and instead focus on throwing technically solid punches with good footwork.
There's a fight waiting to happen ,,say one thing & do another ,but anyway,,,, For beginner straight 4,,,,bob, straight 4,,,,making sure palms on fists are facing down on impact & all left /rights hit the same target area Advanced,,,,lets say you have your opponent on the ropes ,,hit with straight 6 puncher's then lean away onto the back foot (don't move your feet),,then fire straight back with power punches ,,straight right left hook The reason is ,,,with the fast 6 punches he will have is guard up ,then by leaning back he may think you have stepped away or he will look throw is guard ,,,so then he will not see the straight right ,,the left hook is just for back up if the right doesn't get throw,,,practice this on the bag ,the quicker you get with the lean back the harder the straight right will be