Hi Frank, Happy New Year and welcome. I'm relatively new around here too, having returned to collecting recently after a long lapse since boyhood.
Sounds like you're already enjoying finding and buying interesting coins at sensible prices. £16 for a really nicely designed, 116 year old bit of silver in perfectly acceptable condition is a bit of a result, really. That said, I do agree with the advice others have already given about how it can be worth paying a bit more for one that's a fair bit nicer. I bought a 1900 halfcrown about 6 months ago from the colincooke.com site which was graded GEF by them and which to me looked absolutely lovely for the price being asked.
As you might have seen in another thread in this area, I went to the Midland Coin Fair last month and would certainly recommend it as an experience in terms of getting to look at loads of coins, and asking questions. I met Rob there too, and bought a coin from him!
Have fun collecting. I agree that there's no need to have a theme or anything, but I suspect that some denominations or monarchs will naturally appeal to you more than others. Personally, I wanted a decent grade example of every circulating predecimal denomination from the quarter-farthing to the crown, and a decent grade example of every monarch. Ideally I would like a decent example of every monarch's bust going back to say George I, but that's probably too ambitious for my coin cash flow!
As a general rule for my coin cash and given the sort of collection I have, I would rather buy a better grade example of a relatively common date for a given type of coin, than a lower grade example of a rarer date. However, for any general rule there will inevitably be exceptions, especially if those exceptions appear to be available for a good value price in my opinion. As an example, I bought a 1905 shilling about a year ago from this very site. It's 'only' NF/AF but is a good honest coin which I'm delighted to have.