When my little guy was two months old, I remember saying to my husband, "What's the big deal with sleeping through the night? Our baby sleeps through most nights..." Two months later, life was different.
The best advice I have is put your baby on a nap schedule and try to be consistent about it. Getting enough sleep during the day helps babies sleep through the night. When they are tiny babies will sleep anywhere through any noise when they need it, until they are done.
Around 3-4 mos, they start having a hard time doing that. They start needing to sleep in chunks in more controlled circumstances.
After about two hours awake, they need to nap. Watch for sleepy signs, rubbing eyes or ears, glassy eyes, fussing, and lay him down right away (nursing down, laying down and rubbing tummy or head softly, singing, whatever works for you).
You will see a big difference in night waking.
Other things that might help: develop a bedtime routine, keep room dimly lit or dark at night, don't talk or play with baby when he wakes in night, not every night sound is waking up (they often make little noises and go back to sleep, count to five before going to him until you can tell the difference).
For help understanding baby's sleep needs, read Healthy Sleep Habits, Happy Baby by Dr. Marc Weissbluth.