Are you looking to settle down or to date?
Choose your site/app based on the outcome you want.
Be honest about what you want up front.
Take time on your profile. This is the first impression someone is going to have of you. Again, consider what you're trying to attract. If it's dating, make is snappy, easy to read and fun.
If you're looking for the one, well you don't want someone who's going to take half an interest. Take your time, pour your personality into it. Talk about what you are and mirror it with what you want.
Choose your pictures carefully. Don't load up with selfies. Have a selection of candid images (social ones), ones dictating a hobby if you have it, ones of you in a relaxed setting (you know the way a partner is eventually going to come to know you, sat down with a book and a glass of wine), throw in a flattering done up photo. Give them a range to browse. Attraction is a huge part of any kind of dating.
Don't accept an offer from just anyone who shows an interest. Don't be afraid to build a connection online first. You're far less likely to be ghosted by someone who has invested time and effort into getting to know you without any chance of immediate physical reward.
Most importantly, relax into it and let it be part of your life but not a focus. Frustration and desperation can seep into your messages. It's meant to be fun, not a chore. If you find yourself getting frustrated, take a break from it. Come back refreshed.