O3 or H beta filter for for nebulas. I started with an O3, which helped are the North American nebula. I like lumicon brand filters.
A moon filter is nice to reduce the brightness of the moon. I think mine is a 13% filter.
I bought a threaded 2 to 1.25 inch adapter so I can use my 2" filters with 1.25" EPs (eye pieces).
I really like Pentax EPs. If your scope accepts a 2 inch EPs, the 30mm is great.
https://smile.amazon.com/dp/B081VG6SGV/ref=cm_sw_r_apan_i_FVEPG59SDVR57BEWZY2D
I have a Meade UWA 20mm 2" that I really like. Not sure if it's available any longer, but it was much cheaper than the Pentax, like $130 I think. I think it's 82° field of view. The Pentax are 70°.
Check out B and H photo or Amazon.
I bought a farpoint brand laser collimator. A Cheshire collimator is a good option too. You can order farpoint and lumicon (same company) directly from their website.
What kind of budget are you working with?