First of all to increase the chances of getting an airdrop you should check the project's airdrop criteria.
For example I am right now participating in the Prom Testnet Campaign. It fits your description of testnet activity perfectly: you claim test $PROM from the faucet, make transactions, mint NFTs. By the way it's a cool campaign with a 1 million $PROM prize pool when the mainnet will launch.
But the thing is - referrals are not necessary for successfully qualifying to be one of the winners. Of course, there is a single task that requires you to invite 1-3 people. But all it gets you is one multiplier to your daily score, so if you find it difficult to invite other people, you are not under obligation to have this multiplier. And you also can increase your multiplier by doing other tasks, like twitter, discord and telegram activities or deploying a smart contract if you got the skills or at least are willing to learn. There are a dozen tasks that add multiplier, so missing a single one you strongly dislike is not a problem at all. Well maybe your overall result may be 1-2% less than it could have been. So what, big deal! I still get enough of Prom Testnet points to qualify for success.
So that's kinda a fun part. I am not very keen on inviting other people to join my referral links, cause I'm not some huge influencer with a lot of followers. So I really appreciate the fact that Prom Network does not force me to invite people to have success in my endeavours.
But other projects often do. I once participated in a project that required inviting referrals - which i didn't do, so I got an airdrop but it was like 10 times smaller than for people who invited referrals. Since that moment I actually never participate in projects where referral links play the major role. I know my strength and weaknesses and try to use this knowledge when picking a project. This is why I actually picked out Prom - Prom Testnet activity requires consistence: doing test transactions every day for months. This i can do easily and with minimal effort. And inviting others is a big no in my books.
So my best advise to you - pick projects that have clear criteria for airdrop and choose the projects that you will feel comfortable about.
I feel more confident doing a single Prom Testnet Campaign than doing 10 other projects with requirements that I will find inconvenient. And i have reasons to believe that Prom will also be more profitable than those.
