I know exactly what you mean. I had a really hard time starting out, probably because of my anxiety about it. Try to relax (easier said than done, I know), because once you stop freaking out things automatically get a lot easier. Focus on safety for now, rather than little details. Before you leave a room, STOP and make sure that all those safety measures are in place-- low bed, alarms turned on, mats on the floor, call bell in reach, correct side rail position. IMO, if you have all that stuff taken care of but you forgot to brush someone's teeth or missed an incontinence check, that's okay. It's better than finding someone on the floor later!
I'm guessing since you asked about dressing people that are working day shift. Part of how you structure your day is going to depend on facility policy and also the type of residents you work with. Are you allowed to get people dressed before breakfast? I worked at one facility where the trays didn't come up for like an hour so I would try and get as many people dressed as I could. In the place I work now the trays come up right away and we are not allowed to dress anyone-- we just do a round of incontinence checks and then pass out the food, but I always make sure that as I'm checking people I'll go grab their wheelchair from the end of the hall and throw all the stuff that I need (towels, clothes, briefs, hoyer sling, and their basin of supplies) in the chair and that way I can make a mental note of any of their supplies are missing so i don't have to go running around later. If your unit has a lot of total care residents that are not alert, you can wash them on your own time but you'll probably have to make time for a lot of incontinent checks, whereas a unit full of alert patients will take longer to dress because some of them are picky about their routine, but most of them won't need much from you after that.
One thing that makes no sense to me is when CNAs wash a person up and put a shirt on them and leave them in bed. Then when they're ready to get them up they have to spend 50 years putting on pants, brushing teeth, looking for their shoes, etc. And then they wonder why they're behind schedule. I noticed that the people that do this are always the ones with the time management problems.
On the unit where most people are total care, after breakfast I do an incontinence check on half my people and then I dress the rest of them. Then I go back and dress the first group and get them up immediately, then I go and change/get up the 2nd group. That way everyone gets an incontinence check 3x before lunch. It's much easier to keep up with your incontinence care if all your people are in bed because you can change them by yourself. But watch the clock because you don't want to have 3 or 4 residents still in bed 10 minutes before you're supposed to go to lunch! If you're new and slow, chances are you'll just have to aim for getting everyone dressed and that's it. If you're dressing someone and leaving them in bed, put their pants and socks on too. Pull the pants up around their thighs and if they use the hoyer, put the sling next to them in the bed.
One thing that can suck up a lot of time is waiting for help with transfers. What I do is I get the resident all set up for the transfer before I ask for help, because that way if the other CNA is available immediately, I'm not making them wait. This means I have the person's clothes on and the chair and hoyer lift (if necessary) in the room. If the other CNA is in the middle of something I usually help them finish what they were doing and then we go do my resident. If I do get stuck waiting in the room I'll do something that doesn't matter if they're in or out of bed for, like mouth care or shaving. Basically you do not want to be standing around for any reason. CNA work is never done, so you should always be able to think of something to do!
Basically you just have to get to know the residents and their routines. i am pretty creative when it comes to finding little ways to save time but most of them are resident-specific so they wouldn't be much help to you. Just remember to calm down and check for safety. Those should be your priorities right now. If your facility doesn't provide "brain sheets" then you should definitely make your own. For me personally, it helps if I write things down. Like if I skipped brushing someone's teeth or I noticed someone's fingernails were dirty and I don't have time to deal with it immediately, I write it down and cross it off later. Otherwise, I keep thinking about it and I get frazzled. That's another reason why I like to finish what I start and then move on to the next thing. I work with some CNAs who can never get out of their own way and they're always disorganized and will run around starting things but not finishing them.