My paper seems to not want to feed properly it suddenly shifts to the side....Cannon ip3500

Make sure you fan the paper properly and it may need a new separation pad, also make sure the side guides are tight on the paper and the paper can't move around.

Did you check, nothing is in the paper feeder? Could be just a little piece of paper or a staple is blocking proper functioning of the feeder.
Keep the paper try clean and take care you never drop or leave anything in the printer, that does not belong there.

Get a flashlight and look into the printer where the paper enters (Leave it jammed ). If the end, right side moves slower than the left, it is hitting something , check for a paper fragment from a previous jam or other debris. The leading edge of your paper should be touching the debris.

Your paper feed is in the back. You are trying to feed paper into the EXIT door. Open the paper access door on the top of the machine, and install your paper so that it is facing you, laying against the door. Paper should feed properly.

possibly that a foreign object, ( label, scrap of paer), has fallen down inside on the left hand side, and it not letting the feed roller catch the paper, the right roller gets it and then it jams. You can get a torch and have a look where the paper goes in to see if this is the case. Dismantling a printer is not an easy job, and it would probably be cheaper on ink to buy a new one.

The paper feeder pads need to be replaced. You may be able to buy these directly from Canon.

Try cleaning the rollers with a cloth dampened with alcohol. You may have dust on them and the alcohol will remove any dirt or glaze.

there should have a wheel (knob)right on the paper exit area, just close it , paper will be come out to front

Refer to this website and follow the troubleshooting steps

http://www.usa.canon.com/consumer/controller?act=SiteSearchResultsAct&functionid=3&fcategoryid=&modelid=&keycode=&startIndex=1&endIndex=15&pageRows=15&categoryType=CATEGORY1&businessType=BUSINESSUNIT&catLevel=1&cuCatLevel=1&cuGuideLevel=1&wtSend=true&srchKey=PIXMA+MP180&searchOptions=Consumer&Submit.x=42&Submit.y=9