Your opponent is pretty bad.
A few pointers in my opinion. Master these few essential combos. xx indicates starter of choice (2a, 5b, 2b)
The 4B relaunch, xx 2c 4b air dash jb/c 5b 2b (2c) 4b jb jc jb jc throw. Omit (2c) for nanaya, aoko, kouma
The corner combo, xx 2c 5c, 5a 5b 5c, 5a 5b 2b 4b jb jc jb jc throw. Your main source of damage.
5C SJ combos, xx 2c 5cc, depending on distance, you could then
a) air dash into jb jc jb jc throw (about half screen)
b) jb/jc into corner combo (from full screen to 3/4 screen)
Deciding which to do comes with experience, and by the time you do the 2c delay 5c, there's enough time to decide which combo is appropriate.
Another handy one would be the 4b into corner combo but the damage increase isn't really a lot.
Practice linking 236b 236b 236b into 623c as this is another important combo for Arcueid. Reps for the combos included below.
Generally, bring your opponent to the corner, and start you pressure game. Arc has combos that cover a lot of screen distance so carrying the opponent should be easy.
Pressure wise I suggest watching more videos of Japanese players like SII and You, and have a read on Tare's guide for blockstrings.
Here are some reps I did while messing about so you have a better picture of how the combos look like. Remember, its all about height control and delaying. So practice practice practice.
Most of the combos are match practical, except stuff in the flashy reps.