Use the downhills to improve the uphills
On the downhill before your uphill, PEDAL! Put it in the big ring and pedal. Do not coast down the hills. It's a waste.
As you approach the uphill, keep pedaling. Change gears as needed, a few cogs, then into the smaller chainring, and then more cogs if needed. You can either stand up to get over the top or simply pedal at a comfortable cadence. That depends on you and your hill.
Once over the hill, do not coast. Put it in the big ring and get ready for the next one. This way, you will be able to sling yourself halfway up the hill by pedaling down the previous hill.