Ideally, you want to use clothing that has the morphs you want. Check before you buy.

You can also use The Tailor (a program sold at DAZ). It allows you to transfer morphs from the character to the clothing (unlike Morph Manager, which can only transfer morphs between similar meshes). The Tailor doesn't work for all situations, but usually you can get something usable out of it.

If you don't want to spend money, you can try to adjust the clothing yourself with magnets. Or see if someone else has done it; with popular clothes/characters, sometimes people make free "fit" poses that adjust clothing to fit.