The cost of paying the gardener could cause problems for OSRS GP Ironman as it's likely to take a lot of farming, so you should stick to the Ultracompost before reaching the point where you can plant your final trees. Keep in mind that you'll be able to help your trees by using this Resurrect Crops spell which is found in Arceuus Spellbook.
Additionally, you can gain certain levels of Farming by using The Hosidius House method in Great Kourend. It requires a 100% favorable relationship with their faction and 34 levels in the Farming skill however it won't take that much downtime between seed growth as a normal method of training.
Simple, straightforward, and easy to learn. With the advent of Winterodt it is possible to do this minigame to get familiar with Firemaking. It is not the fastest technique, however, you'll get plenty of rewards doing it, which might aid in advancing your levels of other skills. Furthermore, it is less boring than the standard methods and there are nearly no prerequisites for it.
To begin your leveling process using the standard method, go to the highest level of Lumbridge Castle and light the logs there, until you're at level 15. At this point until 35, it's best to light Oak Logs that you can cut yourself then your best call will be to select Teak trees for gathering logs. You can keep Woodcutting and lighting logs that are gathered from it or transfer to Winterodt. The efficiency of your Firemaking will be adequate to allow you to enjoy the most enjoyment there once you reach at least level 50. Keep in mind that your Magic or cheap RuneScape gold Redwood logs must be used in the game for Bird House runs, so do not use them for Firemaking.