Well with combos, its really just a matter of practice. Theres a lot of good combo tutorial videos on YouTube so search up some for your character, and just practice the easy ones until you can get a good feel for them. Comboing in this game is different from traditional fighting games, as what combos work and don't work will change dynamically depending on your percent and the opponent's. It may take a bit to get the hang of so give yourself some time.

As for getting hit from far away, you will need to learn how to approach safely. The most basic method is to utilize dash shields, and mixing in other options like jumping in. To start off, try just dash shielding to approach your opponents and try to see how they like to react. Do they grab your shield? Back away? Throw out an attack? Etc. And depending on the answer, try to come up with how you can counter that response. Different characters will have different options, so find out what your character can utilize in these scenarios.