Welcome!
My first piece of advice is to be patient. Give it at least two weeks in the fermenter and two weeks at room temperature to carbonate. Then you need to refrigerate for at least 3 days. Longer conditioning times can help most beers, but some beers (notably IPAs and wheats) are considered to be best fresh. Many people discount the benefits of cold conditioning (longer time in the fridge) because the yesat will be mostly dormant at fridge temperatures, but I've found that refrigerating for 2 weeks or so benefits the beer greatly.
I keg now, but when I bottled, I never used any sugar except for plain white sugar.
Temperature control is probably the next most important thing.
There are a lot of different levels of brewing.
Using the prehopped extracts from Brew Demon or Mr Beer is the easiest (heat water, add can, add cold water, add yeast). You can "doctor" these by adding additional extract, dry hopping, steeping specialty grains, etc. Sometimes, changing the yeast can make a big difference.
Before tweaking the kits, you should understand what the different ingredients bring to the table. Many people recommend brewing them as-is first to learn what they taste like unaltered so you can taste the changes that different ingredients make.
The next step is probably an extract kit, using either LME or DME. These generally require a hop boil of up to an hour.
There are also a lot of recipes available online, where you buy the individual ingredients.
If you prefer, you can create your own recipes instead of buying kits. If you go that route, you'll probably want to get some brewing software like Beersmith or QBrew. Qbrew is free and easier to use, but Beersmith has more features. @screwybrewer has a spreadsheet based program (
https://www.ezhomebrewing.com/) that probbly rivals Beersmith. I've looked at them, but I've been using Beersmith for a long time and entropy is tough to overcome. Screwybrewer hosts a download of QBrew. There are also some online recipe programs (some free, some not).
Many extract kits include either a steeping grains or a partial mash. With steeping grains, you soak grains that are specially prepared in water at a specific temperature for a set period of time. For a partial mash, you need "base" grains that are malted so that they will convert starches to sugars in water for a longer period of time. The temperature and amount of water used for a partial mash are a bit pickier for a mash than for a steep.
Most kits are 5 gallon kits. You can usually scale these down, or split them between several smaller fermenters. There are small batch kits available, but they tend to be more expensive ona per beer basiis.
The next step is all grain. This approach uses no extract and uses only malted grains to get the fermentable sugars.
There are other things you can do (such as work with water chemistry:
https://ezwatercalculator.com/).
Different people progress at different paces. Some people try one or two prehopped kits (Mr/BD), then jump straight to all grain. I brewed prehopped kits for about a year (adding additional extract and/or hops after the first couple of batches), then started creating my own recipes using LME (my LHBS sells LME at a really good price, especially if I buy in bulk), but also continued making some batches with prehopped extracts. I think I started adding steeping grains after about 2 years, and started doing partial mashes shortly after that. I didn't switch to all grain until I'd been brewing for 9 years or so.
It's not a bad idea to do a few prehopped kits first to get the process down and get good at sanitizing everything. But after that, it depends on your comfort level.