Have a look at this vendor's cellular antenna page. As you'll see, there are plenty of solutions for this common problem. This firm is by no means the only one on the Internet which sells this gear, it merely happens to be the only one having a link that I was aware of.
1) Yagi antennas are terrible, avoid wasting time and money.
2) The cheapest solution that gives the more reception is a very tall vertical. I used one like the truckers put on their mirror and put it on the top eave of my roof at 15 ft up and it worked better than anything.
3) If you have bucks to spend and know the direction of the cell tower a panel antenna is a good solution. Often can be mounted under the eave flat against the house.