Yes your machine doesn't have the power to go through many layers of heavy material so it's best to sew that by hand. Use a size 18 or denim needle when sewing heavy materials like denim.

No need to buy anything but universal needles. Most needles are of the same quality. The thing is to use the right sized needle for the job. The rule is the finer the fabric the lower size the needle.
16 or 18 or denim for heavy material like denim or other heavy material--canvas etc..
14 is the size you would use most often. It is good for cottons and like material.

Anything lower than 14 is used for light material. The lighter the material the lower the number.

Cheap thread will cause a lot of problems--breaking tangling etc. So no matter what machine you have it is best to use good thread.

Always stop the machine with the needle in the highest position and leave a good tail of thread. That way you don't have to worry about the thread slipping through the needle or hold the thread back while the needle goes to the highest position.

Generally the tension setting shoyuld be around 3 or 4, but as long as the machine is sewing right you shouldn't fool with it unless there is something wrong. If the tension is too loose it will make a birds nest of thread underneath the fabric. If it's too tight it will pucker the material and break the thread.

These are general tips for any sewing machine. I suggest you read your manual and keep it with your machine so you don't lose it. It is the best trouble shooting guide for your machine