I am wanting to forecast sales of different products within a business.

I have a good background in mathematics (but mainly focused on analysis, group theory, algebra etc. as opposed to statistics).

I also have some experience in Python + related libraries (pandas, numpy, tf, keras) so anything that could use that would be nice.

The information I have is like:

* Previous sales (including when and how much)
* number of customers that are eligible to buy the product
* how big the customer is
* etc...

I do have access to a lot of potentially related information that could be used but I don't know what to choose.

I have considered doing maybe some kind of seasonal time series (as I suspect there is some seasonality in some products) like ARIMA but I am not sure at all.

Also I want to make it quite simple to begin with I don't want to get carried away with fancy statistical methods that are maybe a) don't understand or b) are not even applicable in my scenario.

I am wanting suggestions of areas/methods/techniques that I could look into that may prove useful.

I don't have terrible amounts of data (on average I would say 3 years of data with 12 points per year [sales in month]) so presumably that would make a difference.

Any advice is appreciated and if clarification is needed let me know.

Thanks.