The most important thing to realize is that a child reaches their milestones through learning, through playing, through experience. So the best way to help your child reach their milestones is by providing them with opportunities to do so. In other words, encouraging them to play with other children, encouraging play dates, encouraging them to be in the playground, being in a preschool if you're able to is a great way for them to learn from their peers.
You can also model things for them, and you can play with your children. So if you're working on their ability to match objects, go get a matching game. You can buy any type of matching game. They have things from princess matching games to pirate matching games to Thomas the Choo-Choo Train. Anything that your child is interested in, try to incorporate that into the play, because they'll be more willing and able to play those games with you.
Another great way to get them to reach their milestones is through interactive make-believe play and also board games, puzzles, and also using language in every day's skill. Ask simple questions, and have your child tell you elaborate stories, and then use follow-up questions. So that they're working on that language and communication developmental milestones as well.
The most important thing to know is that parents have a very strong impact on your child's development. So you really have a lot of control in your child's development. So the more opportunities that you present for your child, the more that they will be able to learn, play, grow, and laugh.