If you have children and still may want more in the future, the classic method for you is the coil.
It's not the only option, though: even if you're over 35, you can still take the Pill as long as you're not a smoker. The same goes for the patch or vaginal ring, which contain the same ingredient as the Pill, administered in a different way.
The implant could also be a possibility for you, but as with the coil, it will need removing by your doctor should you decide to try for another baby. It's a long-lasting contraceptive and is effective for several years, which makes it ideal if you want to space out your pregnancies over a certain period of time. It's not as practical if you're thinking about having another baby relatively quickly.