In very early game if you're playing with an aggressive adc, you can go e first and try to look for an e on the ennemy botlane early. If things go bad, if you have phase rush, you should be able to zoom out. If you don't have an aggressive adc, you should wait for lvl3. Once you have lvl3 you can play aggressive, If you hit the full W>E>Q combo you can safely escape with phase rush afterwards and get free trades.

Look for fights with your ult, and your e. You are strong at this point, if you play the fights properly you should be able to win 2v2. Beware, can't miss an e at this point or you get one shot. If you're looking for a combo guide, i don't have one, however i have this small youtube short about how to make the best combo (imo) on gragas : here

YOU ARE STILL A SUPPORT!! Don't be annoying, don't take waves, your biggest strength is your peel. Your e, your everfrost and your ult are great tools to provide for your strongest member. Now that we went over that.. you do damage! You can also look for flashy plays and crazy e flashes, or ults on the backline to get them onto your frontlane. You have a lot of tools to offer. But seriously, if you have a strong member, you will win the game if you sit on top of him and E people who try to get onto him. Just setting up for your teammates is what you need to do at that point, you do less damage than damage dealers, you tank less than tanks, you peel less than enchanters.

If you guys enjoyed this guide make sure to come by the stream here, i'm a master EUW player at the time of making this guide, I main Gragas, however i'm not a one trick and i play a lot of different stuff so you might not catch me on the champ!

(All the infos are on the notes within the guide, make sure to check them out!)