Common

After clicking Play, I'm stuck at Multicharacter screen

That issue is mostly related to the framework issue, or something that prevents the player from loading. Make sure that your framework runs correctly.

I got black screen after selecting character

That issue lands in some of your assets with wrong usage of DoScreenFadeOut (if circle progress is seen in bottom right corner).

I'm stuck at logo screen

Mostly there's some server side error which you can check via txAdmin > Live Console. If there will be some redirect to our docs page, you got clear view how to solve that issue. If error is not visible there then it can be related to the infinite requesting model of the player ped (previous output should be Preparing entity [/]). To solve that you need to check if the model saved in database is correct one.

Skin of the player is not correct

That's because you haven't applied the appearance correctly. Check out the installation of it here.