I usually carry useful things while travelling but I cannot manage to place all my things like clothes,shoes,and accessories.Is there any effective way to put all these things in a small suit case?
Empty space is your enemy. Compress clothes and other things as much as you can. If something can't or shouldn't compress, put things inside of it -- like rolling up your socks and shoving them inside your shoes before packing them.
Also, only take as much as you need. That includes toiletries. Don't take a whole bottle of shampoo (even a small one); buy a set of travel containers, and just take enough shampoo for the trip -- or even omit shampoo altogether and use the shampoo at the hotel you're visiting.
There may also be large items that are inexpensive, so you can buy them when you arrive. For example, you can buy an umbrella for under $5 (usually), or contact lens saline solution for about the same.
Packing cubes also help items fit while keeping them organized. Many outdoor/travel companies have their own models and some are even compressible (which is nice for bulky items like sweaters).
Another tip is to wear your bulkiest shoes during travel (for example, wear your boots and put sneakers or sandals in your suitcase).
In addition to BrettFronLA's answer, I've found that rolling your clothes (trousers, shirts, etc.) takes much less space than just folding and pressing them inside the suitcase.