Ways in which to help speed up my laptop

Lately I've noticed that my laptop has been running a lot more slowly. Also it seems as if that the bottom of my laptop is very hot sometimes. I've tried deleting and freeing up space on the HDD but it doesn't seem to have made a difference. Ran a virus check with AVG and MalwareBytes too with nothing showing.

Was hoping if anyone could help me with some procedures or maybe some programs that might help speed it up.

Clean your laptop ventilator.
I clean people's laptops around my place for a small fee (Costs 25/30 euro) and I ask 10.
I do it for free for my friends and relatives of course.

Anyway, they all love the improvement in their laptops.
Heat is your number one enemy, not memory issues.. unless your laptop isn't hot.

Just so you know, it's not a big deal cleaning your laptop but you still
have to be careful nonetheless with the wires. (Especially if the you need to
fiddle with the screen wires). My own laptop is a mess to take apart for example,
but my mothers is really quick and easy.

Here's my messy one:


I was dumb because I messed up the keyboard a little bit.
Now it's bulging a little bit after I put it back in.