I like to ask you for your advice about manga,hentai manga and such if you don't mind helping me ahead of time

When & if i buy manga hardback or paper back do you have any tips on how to decide on what manga should i buy or is it better to buy any manga whatever I'm in the mood to buy,get,add to my collection & to read? I apologize if this sounds like a dumb question i admit sometimes it's hard for me to pick and yes i know some are cheap and some are not cheap and some box sets are cheap and some are not cheap i admit sometimes it's hard to choose what manga to buy,add to my collection and to read & if i choose to and I'm just wondering if you do have any tips on how to decide or is it better to buy any manga whatever I'm in the mood to buy,get,add to my collection & to read. Thanks for your time,thanks for your understanding & thanks for your tips and before you ask don't worry I'm including hentai manga & doujinshi if you want me to and if you wish to include side tips for them too as well then that's fine with me only if you want to thanks again for the help & your tips ahead of time when & if i ever do buy anymore in my collection :).

Personally if I see a manga that looks good I try to at least read the first few chapters online to see if it's something I can dig. I used to just buy it without seeing a sample and was disappointed so many times.