You have a couple options. If you go with a basic fan/light, you can use a single switch and then control fan and light functions via the pull chains. If you get a fan with a remote, you can use the remote to select between the fan and light. You can also add on a remote to most fans.

Thank you Tom9951.
I have one more question on fans. Not sure if this is the right forum.
Is higher the cfm better or higher the rpm.?
Found 2 fans I like, one has 6000+ CFM with 140rpm and another with 4500cfm with 160 rpm.Not sure which one to go with.

I'll guess the higher CFM has more/larger blades. Do you have the room for that? The higher the RPM the harder it is to balance (at least in my experience)

The room is a little less than 300 sq ft. with 12 ft ceiling

I purchased the ceiling fan. The downrod is only 6 inches and the pull chains are also 6 inches. If I install this in my 12 feet ceiling I would not be able to reach the pull chains to operate the light. Can I buy long pull chains to operate this fan/light combo.( which has only 1 wall switch for the existing fan only). Would hanging a 3ft or 4ft long pull chain cause any problems. Since increasing the length of the pull chains is the cheapest option compared to buying a downrod($20) remote($35) or extra labor for an electrician to install dual switch .
Please suggest. Thanks in advance.

I think the original answer gave you the best advice in buying a fan with remote control. You would then always leave the switch on and use the remote for light, fan speed, fan direction, dimming light , you name it.