(1) do not worry or concern yourself with things outside your control.
It's irrational. It makes no sense to stress about things that you can literally do nothing about. Death is the obvious example, but there are several others. Don't worry about what other people think of you, or luck, fortune, or fame. Don't worry about what your kids are doing. Stop controlling other peoples' freedom. Is there an election coming up? Then cast your vote. Are you hungry. Then eat. Will that person you hate be at the party? Then don't go. Or go. Might the weather destroy my crops? Then plan. However, some things are not so clear-cut: global warming, world hunger, war. These are global, general, constant worries. It requires wisdom and discernment to figure out how much you ought to worry, based on the amount of responsibility, time and effort you decide to give to particular causes. I'm not sure what the Stoics thought of prayer, but I'm guessing prayer is a good exercise as long as you not praying instead of acting (in other words, it's okay to pray for things beyond your control, but don't get bothered when God doesn't oblige). The world will constantly bring random events, some good, some bad. The Stoic accepts everything from God with a heart of grace and thanksgiving. God (or the Gods) know better. And even if the Gods do not exists, Aurelius says, that's outside our control too! Therefore, still accept serendipity and tragedy with grace.
(2) for those things within your control, accomplish them.
Once you get rid of all the crap filling your head, it's amazing how well you can accomplish your real tasks in life. Know thyself and do thy duty. This is the creed of the Stoic. Know thyself. Are you a good person? Do you constantly question yourself? At the end of the day, do you take stock of your life? Examine the depths. If you know yourself, then you don't need to look to others for the answer. Are you best suited to be a doctor? Then become one. Do your duty. Purge vice and seek virtue. Do the things that need to be done and ought to be done. Simple as that. Living this way, people will think well of you (without you worrying about it). When you question yourself and live the best life you can, everything else falls into place. Perfect your talents, eat healthy, be graceful, forgiving, friendly. If someone has wronged you, go talk to them and work it out immediately, as Jesus also taught. Never let things fester in your soul; purify it constantly.
Stoicism, in my view, is extremely compatible with the teachings of Jesus and Kant.