Need suggestions for windows film

This is very common in some of the hotter parts of Tamilnadu, Tiruchy etc. I saw all houses with this. Unsure of costing or brands for houses, but in cars I know 3M is a good brand. You need to consider greenhouse effect when you install this. It is advisable to install this on the outside of the windows and not inside, is what I have read. Please google it before taking the plunge. I myself was considering this for my bedroom, but a cheaper alternative of sticking black one sided color paper on the inside part so I can use my projector in the day times.

Covering only the window glass with sun control film will not completely reduce the heat because even the walls heat up increasing the room temperature. (more in the afternoon in west facing rooms) If your ac room's roof is also directly exposed to the sunlight then it is another factor adding to the increase in room temp. You can clad the walls and roof with hollow clay tiles (SEE LINK BELOW) to reduce the heat...or if you grow some plants/trees/ivy over the walls and roof it can also help reduce the heat build up.
http://www.btiles.com/wall_cladings/clay_wall_claddings.html

Other cheaper options can also be tried : like bamboo screens which can be hung outside to prevent the sunlight hitting the window panes. A more expensive but more efficient solution is a double glazed glass pane...this will have two glass panes with a air gap between them (this also reduces outside noise) Even without sun film this will reduce the heat but definitely be much more effective with sun film. .

I've tried planting a lot of plants but damn pigeons kept on laying eggs in flower pots. I now just have a long creeper creeping around the window grills. We live in 4th floor and apartments water tank is directly above our flat. Also we already have surya cool home paint painted on the terrace space which is above our flat.