My favorite gardening tip is learn to graft. It will unlock so many possibilities.
Tropical fruit trees can be very expensive especially rare variety. Once you learn to graft, you can use existing big rootstock and even rescued huge tree to graft it to. It will grow faster with vigorous rootstock and fruit faster.
I've seen Thai ruby seedless guava selling for $2000+. If you know how to graft, you can graft, you can save significantly
My other tip is learn how to rescue tropical fruit trees. Establish tree take a long time to get to that size especially in subtropical regions and very expensive to buy. If you know how to transplant tropical fruit trees, you will save alot of time and money. You can rescue any trees and use it as rootstock to graft better variety to it. I've rescued cherimoyas, atemoya, wax jambu, mangos, guava, citrus, etc and they survived.
My third tips is to learn how to airlayer and try to airlayer big branches if you can. I always try to aim for 1.5-2 inch branches. It takes longer to get adequate roots, but it will give you more of a stronger tree and fruit faster.
Fourth tip is to network with other gardeners in your area. You can trade scions and fruits that you may not have or tasted. It's always nice to talk to people about your hobby and do garden tour.