You are going to purchase apartment which will be built on a piece of land. Therefore, the first and most important is to check the tile of ownership of the land.

While purchasing apartment from developer ask them whether they purchased the land. If they purchased the land check the previous ownership of the land- is the tile of ownership is unbroken, will anybody emerge as successor or with preemtion right.

In maximun cases developers go for joint venture with landowner ( i.e. 50-50 ratio or something like that). In such situation you shouuld see the contact paper (power of attorney) which has been signed between land owner and developer. Here be sure that whether developer is entitled to sale the apartment that you desire to purchase. For example, in a 6 storied building land will get 3rd, 4th, and 5th floor and developer will get remaining floors. You can not puchase apartment in land owner floors. You should also check the title of the ownership of land like previous way.

Also check whether the project has RAJUK approval or not.

It is better to take help from a lawyer to avoid future dispute.

Ask the developer how many projects they have already handed over. Talk with them who already got hand over to know the developer.

One important thing, first bargain(if possible) and determine the price then go for check.

Lastly, for any purchase don't be confused once you purchase a product. Take any disliking situation easily.